HUBERMAN LAB PREMIUM • ASK ME ANYTHING • EPISODE #11
AMA #11: IMPROVE TASK SWITCHING & PRODUCTIVITY AND BRAIN FOG
ANDREW HUBERMAN: Welcome to the Huberman Lab podcast, where we discuss
science and science-based tools for everyday life.
[MUSIC PLAYING]
I'm Andrew Huberman, and I'm a professor of neurobiology and ophthalmology at
Stanford School of Medicine. Today is an Ask Me Anything episode, or AMA.
This is part of our premium subscriber channel. Our premium subscriber channel was
started in order to provide support for the standard Huberman Lab podcast, which
comes out every Monday and is available at zero cost to everybody on all standard feeds- YouTube, Apple, Spotify, and elsewhere. We also started the premium channel as a way
to generate support for exciting research being done at Stanford and elsewhere-research on human beings that leads to important discoveries that assist mental health,
physical health, and performance.
I'm also pleased to inform you that for every dollar the Huberman Lab premium channel
generates for research studies, the Tiny Foundation has agreed to match that amount, so
now, we are able to double the total amount of funding given to studies of mental health,
physical health, and human performance. So without further ado, let's get to answering
your questions.
The first question is about task switching. And the specific question is, is there a way to
get better at task switching? Well, task switching is an incredibly interesting topic. It's
something that plagues many people. That is, a lot of people have challenges with task
switching.
It's also a topic that people will often confuse with cognitive flexibility. So all of us-- well,
unless it's been removed-- have an area of our brain called the prefrontal cortex. The
words, "prefrontal cortex," actually refers to fairly varied real estate within the human
brain.
So it's not one area of the human brain. Prefrontal cortex actually includes a lot of
different subdivisions that do different things in the context of cognition and directing
action, withholding action, these kinds of things. But one of the main functions of the
prefrontal cortex is that when it's working well, it allows us to direct our focus and our
cognition, our thinking, in a context-dependent way.
So one of the simplest ways to describe this is that when you took math in high school or
if you're still taking math, your brain had to carry out certain types of cognitive
© 2023 Scicomm Media LLC
1
operations that were very different than the types of cognitive operations that you need to
carry out in your history class or your social studies class. But there were some features
of all three of those classes that were the same, in the sense that presumably, you had to
sit in a chair for all of those classes, you followed a certain set of rules that pertain to all
three of those different classes, even though they're different subjects.
But then, there were certain rules that pertained just to mathematics, certain rules that
you followed because the particular teacher was strict, not because of the topic they were
covering, as well as certain rules that maybe you did not pay attention to, because a
different teacher was a little more lax. For instance, maybe there was a teacher that let
you put your feet up on the chair in front of you. Maybe another teacher forbid that at all
costs.
The point being that your prefrontal cortex is the area of your brain that, along with other
areas of your brain, ensures that you engage in context-specific behavior, context-specific
thinking, and context-specific understanding about what you should and should not do.
Now, cognitive flexibility is similar, in the sense that it describes your ability to switch the
types of cognitive operations, as the name suggests, depending on what sorts of things
you're trying to learn or understand.
And it's a lot more extensive than that. In fact, we will probably do an entire episode all
about both cognitive flexibility, and perhaps even a separate episode on task switching.
But task switching is somewhat distinct from cognitive flexibility. First of all, task
switching requires cognitive flexibility, but they are not the same thing.
Now, when we talk about task switching, or rather, when you see task switching in the
scientific literature, most often, it has to do with people performing one particular type of
mental or physical operation. Say, they're maneuvering things with their hands or other
parts of their body, or they are required to carry out one specific type of mental process,
and then they are required, either at random intervals or at specific intervals, maybe
every 10 minutes or so, to switch their attention and to do a different task entirely.
Now, in the laboratory experiment situation, this has most typically been carried out the
following way. People are going to do one cognitive task, maybe mathematics, or they're
going to count, for instance, from 1 up to infinity, as high as they can go in a given
amount of time, in increments of, say, seven, or increments of 7 plus 1, then 7 minus 1.
So these can be made increasingly difficult. You get the idea.
And then, perhaps a tone is played or they'll get a signal from the experimenter, and then
they need to switch their task to doing something quite different, but also cognitive.
That's the most typical arrangement. Or another typical arrangement in a task-switching
experiment is that the person in the task-switching experiment will be asked to do some
sort of physical manipulation of objects, maybe placement of puzzle pieces into the
correct configuration.
© 2023 Scicomm Media LLC
2
Then, at some designated interval or intervals, they will have to switch to a different
manual task. Fewer-- not zero, but fewer-- experiments have examined task switching
between physical and cognitive tasks. OK? Now, there are these kind of outrageous
examples that you can find on the internet.
By the way, I don't suggest that anyone go engage in these examples in real life of
extreme task switching. One of the most notable ones would be chess-boxing. Believe it
or not, this exists, where two people will enter a ring, and they will sit down at a table,
and they will play chess for a given period of time.
So they're entirely focused on playing chess. Then a buzzer will go off. The chess table
will be cleared, the chairs will be cleared, and they will be expected to box-- literally, fight
for a round of, say, a minute to three minutes, and then go back to chess, then to boxing- so-called chess-boxing.
Again, I'm not suggesting people chess-box. But I know that many people have
challenges with task switching, and here, I can raise my hand and say that I am one such
person. I've always had a pretty good ability to drop into deep focus, after a period of
time, you know. I, like everybody else, takes a little bit of time to get into a book chapter
or to get into a mode of physical exercise.
But once I'm doing something, I tend to be very, very focused on that, and I have a much
greater challenge in switching out of that focused mode to doing the next thing, which is
one of the reasons why oftentimes I run tardy. Because I'm still mentally thinking about
or physically engaged in the thing that I was doing before. This is something I'm
constantly working on.
And as a consequence, I've had to seek out and implement certain tools to improve my
ability to task-switch. So I'm going to share a few of those tools with you now, because I
know a number of people probably struggle with the same thing. And as I mentioned
earlier, I'm also going to do a full-length episode about task switching, both the
underlying mechanisms of task switching as well as a more extensive list of tools related
to task switching as a full-length Huberman Lab podcast episode.
So how can we get better at task switching? Well, short of having somebody scruff you by
the neck and force you to stop whatever activity you're doing and engage in the next
activity that you're doing, one of the best things that we can do to support our ability to
task switch that's nicely supported, both at the mechanistic level and at the practical
level within the published literature, is to introduce short transition gaps between the
activities that we're trying to switch between.
This is something that, in my opinion, has not been discussed enough. In fact, when was
the last time you heard about the requirement for introducing gaps between tasks if you
want to switch between them more efficiently? And yet, as a consequence of this not
© 2023 Scicomm Media LLC
3
being discussed very often, I think a lot of people have placed an undue burden on
themselves.
For instance, a lot of people think that when you sit down with a book and you're going to
read, that you should be able to immediately focus on the material that you're reading
and not have your mind flitting about. During the first 5, maybe even 10 minutes of
reading a book chapter, unless you are absolutely enthralled from the first word or you
are intensely curious what the material in that book chapter is-- maybe that book chapter
is about you and what's going to happen to you next in your life, maybe the news article
is about something that you care oh-so-much about.
But unless it's one of those specific instances, it's going to be about 5 or 10 minutes
before the neural circuits in your brain that are required to understand and digest and
commit that material to memory are going to come online at the levels of activity that are
going to be required for you to experience that as intense focus, or even as mild focus.
Because the activity of the brain is always going to be in a push-pull. This is extremely
important for understanding task switching.
When you go from one task-- and maybe the task is simply to walk over to where the
book is located-- to focusing on the material within that book, you have to both engage
activity within certain neural circuits, and you need to disengage the activity of other
neural circuits. Now, sometimes this is referred to as inhibition of certain neural circuits.
Other times, it's just going to be a dissipation of activity of those neural circuits.
They're just going to quiet down, like a dimming of the lights in a particular room, while
the activity of other neural circuits increases. OK? So the first thing that you really need
to understand if you want to get better at task switching is that you cannot and you
should not expect yourself to immediately drop into a narrow trench of focus or a narrow
trench of ability for anything that you're not already extremely skilled at or extremely
interested in knowing. OK?
One of the reasons why this is often overlooked is that, for instance, if we receive a text
message from somebody and we are very interested in what's contained in that text
message, maybe even eagerly anticipating the dot-dot-dot in that little window where the
text message is going to arrive, like here it comes, here it comes, here it comes, it's an
example of where you are able to immediately pay attention and absorb information. For
instance, if you're trying to meet somebody in a big city and you need to know exactly
where to meet them and you've arrived at the place where you thought you need to be,
and then you can't find them, and you're waiting, waiting-- where are you? Where are you?
And you know, you're going to commit that information to memory, and you're going to
act on it. But when you sit down to read a book of unknown content, or where you have
just a general sense of what the content is, or when you sit down to do something like
work on a spreadsheet or your taxes or engage in a conversation with somebody, expect
© 2023 Scicomm Media LLC
4
a 5- to 10-minute transition period. I can't emphasize this enough, because I think a lot
of people mistakenly think that they have issues with attention, and perhaps indeed, they
have clinically diagnosable attention deficit hyperactivity disorder or some other form of
attention deficit disorder.
Certainly can't rule that out based on this conversation alone. But a lot of people place
this unfair burden on themselves to immediately be able to focus on a given task. And
this is also true for physical tasks, right?
If you go to the gym to work out or you're heading out on a run or a cycling expedition,
the idea that you would immediately be able to cycle at your peak performance or that
you could perform sets and reps in the gym as best as you possibly could without any
warmup, without any transition period-- that you could forget about the difficult or maybe
even great conversation that you were having on the way in, or that you could forget
about other activities that you need to do in the rest of your day-- I mean, that's just
completely unfair, and it doesn't match at all the way that your neural circuits work. So
you really need to match your expectation of your ability to focus on and perform a given
task, whether or not it's cognitive or physical, to the actual underlying biology. OK? So
that's the first point.
The second point is that we know that if you want to switch from one task to another
task, that you are making it more difficult to drop into full task engagement, or rather,
engagement with task B following task A, if you try and go immediately from task A to
task B, that even the introduction-- I find this so cool-- even the introduction of an
arbitrary but very short transition period of, say, 15 seconds, where you know that you're
introducing 15 seconds of transition and you designate it as transition, will allow you to
engage in a more efficient and more complete level of task execution on task B, if you
introduce even a brief transition period.
Now, this, I find fascinating. Because what this means is that there are top-down
influences. There are literally things that we can tell ourselves, based on an
understanding of the underlying mechanisms, that allow us to task-switch better.
And this certainly doesn't involve taking any kind of prescription drug or supplement or
doing anything differently, except as you go from task A to task B, knowing and
designating that a transition period, even a very brief one, where you are not trying to
perform task B, and that you've designated, this as a transition period-- I'm not trying to
focus on the next thing that I need to do-- I might focus on it inadvertently, but I'm not
deliberately trying to focus on it.
Rather, I'm going to think about what I just did and the fact that I'm no longer doing that,
kind of leaving it like a fog behind, right? You're trying to move from this deep trench of
attention, hopefully, on task A, or maybe you didn't achieve a deep trench of attention.
© 2023 Scicomm Media LLC
5
And you're now done with task A, and you're not placing this unfair expectation on your
neural circuits to just flip to task B.
And you're also acknowledging that task B is going to take 5 to 10 minutes to drop into
fully. We already talked about that. But you're going to shorten that 5 to 10 minutes by
deliberately introducing a transition period. And what comes in that transition period and
its duration is important.
So first, let's deal with the duration. How long should the transition period be? Well, that
is going to scale directly with how long you were in a deep trench of focus for task A.
But let's assume task A was something that was kind of light for you. Maybe you're just
handling some email. Maybe you're talking to a coworker. Maybe you were at a board
meeting and it was kind of light.
The stuff was just, OK, you're used to this stuff. This is the stuff that you do all the time.
Now, you're headed back to your desk, or you're headed to your next class, or perhaps
you did work out that morning, and now, you're going to head to your place of work.
Or maybe you're leaving work and you're going to engage with family. And you know you
need to switch all these cognitive operations. You need to dump the stuff that you were
just doing cognitively, and you now need to do a bunch of other things. Context is
switching. Task is switching.
Well, just ask yourself, how deeply was I entrenched in that other activity? Was my mind
flitting to other things? Or if I was in a deep trench of attention for that given thing, well,
then you should give yourself slightly longer for this transition period-- maybe 5 or even
10 minutes, if you have that time. But even if you give yourself as short as 60 to 90
seconds of transition and you just designate it-- excuse me-- as transition, you're going to
benefit in terms of your ability to do the next task.
So to be very clear, if you were in kind of a light task or something that didn't have much
cognitive demand, well, then the transition period can be fairly short. It can be just a
couple of minutes. Rather, if you were in a deep trench of attention, you really engaged in
that first task, I suggest giving yourself a couple of minutes or more, maybe as much as
5 to 10 minutes. But you might not have that much time, in which case, give yourself any
kind of transition, even if it's 10 seconds.
I certainly have had times in my life, in particular when I was a new assistant professor,
meaning before I got tenure, where I remember sitting down to work on a grant, I'd get
two lines out, and someone would knock on the door. Hey, where are the-- whatever-- the
30-mil syringes? Where do we keep the buffers? Or where's the-- we get this thing?
And OK, and then I'd have to shift my attention and go back to writing, and then I'd be
distracted by something else again, which is not to say that people were distracting me
© 2023 Scicomm Media LLC
6
unfairly. It was simply the case that at that time, my life required being involved in a lot
more things than it did as my career progressed, at least in the short term.
So the point being that if you are deeply engaged in an activity, give yourself a little bit
longer in the transition period between them. If you are sort of superficially involved in an
activity, you need less of a transition period, but you need a transition period. What
should come during that transition period?
Well, the most important thing to arrive in that transition period is a relative lack of
attention to anything new. This is what's so destructive about the phone. And keep in
mind, I am not one of these people that thinks that smartphones are terrible. In fact, I
use mine, plural, very often, all day, often.
Not necessarily during deep cognitive focus, but in between those bouts of focus, I have
to text-message people. I do work on there. I'm on social media. So certainly, not
demonizing the smartphone.
However, if you finish a given activity, whether or not it's a cognitive or physical activity,
and you are headed to something else that requires you do a new task, and that task
requires significant amounts of attention and focus, well, then you would do very well to
allow yourself a period of anywhere from 2 minutes to maybe as long as 10 minutes. I
know this is going to be very hard for people, but 2 minutes to as long as 10 minutes,
where you are not looking at your phone, you're not texting, you're not on social media,
you're not foraging for anything.
In fact, you're trying to limit the total amount of information that you're bringing into
your nervous system. Now, you don't have to walk around with eyes closed and try and
not hear and not see. Let's be practical, folks. That's impossible to do anyway. You can't
shut down your brain while awake.
You can go into states of deeper relaxation. There's non-sleep deep rest, which we'll talk
about in a little bit. But you can't shut off your brain deliberately, OK? Not in any healthy
way, that is.
But by introducing these transition zones or transition periods, as we'll call them, of 2 to
10 minutes between different tasks, and making sure that within those transition
periods, you are not bringing in new information-- again, another context-- and what are
you really doing? Well, you're ensuring that you're not going from task A to task B to task
C. What we're talking about here is trying to limit your task switching between task A and
task B and not introducing another task in between.
And you might think that looking at your phone is not a task, right? It's so easy. It's so
reflexive. But it is. It's bringing in a lot of new context-- in particular, pictures and movies,
which are a tremendous stimulus for the nervous system and anchoring your attention.
© 2023 Scicomm Media LLC
7
It's bringing in new ideas, new thoughts that, no matter how hard you try, are going to
intrude into your ability to perform task.
So when people say, how do I get better at task switching, I immediately want to say,
please don't introduce yet more tasks. Switching from one task to another is hard enough
already. Don't introduce another task in between.
Now, some of you might take this to mean that you shouldn't have a conversation with a
coworker after a meeting while walking down the hall. I'm not saying that. I still
encourage people to be social. I encourage people to engage in workplace environments.
However, I will say after many years of working in laboratories that at times were quite
large-- you walk into the lab and there are a lot of different things going on-- one of the
things that you learn how to do, if you're going to get good at your craft, is to not pay
attention to what's going on with everyone crowded around a computer looking at who's
winning at the World Cup. I'm not trying to insult soccer players here. I enjoy soccer,
both playing it and observing it.
But one has to scruff themselves a little bit in trying to limit their attention to a number
of different things in the environment and really go from task A to task B in a really
dedicated way. Short lists benefit certain people. I know a lot of people are listmakers
out there. They like to put two or three things, or maybe 20 things that they're going to
accomplish each day.
One of the best tools that I ever learned, both for the sake of task switching but also for
sake of just getting things done on a consistent basis-- I picked up while I was a master's
student at Berkeley-- a very accomplished professor at that time told me that he writes
down, every day, three things that he's going to accomplish and only three things, never
more than three.
Now, he also included other activities. In fact, he was quite active in his physical life, so
he rode his bike to campus. He also was a runner. He also went to the gym. He did not
include those on his list of three things, but he would write down no more than three
critical things to do each day.
So he had three critical tasks. So I've employed that method as well. I'll write down one,
sometimes two, most often three, but if I can, just one or two tasks that I need to
complete each day. And everything else is considered part of the, let's just say,
automaticity function of my day-- things that I already know how to do that don't require
a ton of cognitive focus.
But I limit the things that require a lot of cognitive focus to three things per day.
However, those three things per day can take up many, many hours each, and certainly
on the whole. OK, now, there are additional things that one can do to improve your ability
to task-switch.
© 2023 Scicomm Media LLC
8
And one of the things that I found particularly beneficial is not a meditation, but rather is
a perceptual exercise. And this is a perceptual exercise that I learned about when I was a
graduate student, but in a totally different context. And it has to do with the way that
your visual system and the parts of your brain that parse time are related to one another
and influence one another.
Now, the reason this tool makes sense for improving your ability to task-switch is
because it turns out that where you focus your visual attention strongly influences the
way that your brain parses time. So I'll describe the tool first, and then I'll get a little bit
into the underlying mechanisms. But again, I'll get deep into the underlying mechanisms
as well as the tool-- as well as additional tools in a future episode about task switching on
the Huberman Lab podcast.
So if you were to, for instance, close your eyes and not look at anything in your external
environment, and just concentrate, for instance, on your breathing or the feeling on the
surface of your skin-- I know this is starting to sound like meditation, but trust me, it's
not meditation-- your perception of time-- that is, how finely you are slicing time-- would
be distinctly different than if you were to open your eyes and focus on a faraway location- say, way off in the horizon-- and not focus on your bodily sensations.
Similarly, if you were to focus your attention on some intermediate location, maybe, let's
say, 20 feet away, and simultaneously focus on your internal bodily sensations or the
surface of your skin, your perception of time, how quickly time was passing, would also
be different than if you closed your eyes or if you were looking at some distant location.
So the perceptual tool for task switching is a very simple one, and it's one that, frankly, I
do every morning and have for many years now, and at least for me, has really enhanced
my ability to task-switch.
And that is to just take a couple of minutes, and this really only takes about two or three
minutes. And typically, what I will do is I'll start by closing my eyes. Oh, I should mention
I typically do this in an environment where, ideally, I can see off into the distance,
perhaps from a balcony if I'm in an apartment or a house, ideally outdoors. But if I'm
indoors, I'll still do this. I'll just look as far off into the distance as I can when that step is
required.
But I start off by closing my eyes and, essentially, not looking at anything, but directing
my brain's focus to either the surface of my body, just what it feels like, what it's in
contact with or not in contact with, maybe my breathing. Then I'll open my eyes, and I
will focus on some location on my body, but my bodily surface, like my hand, at some
distance. And I'll focus my attention there, maybe for just 5 to 15 seconds.
I should mention that the first station, as I call them, where my eyes were closed and I
was focusing on my bodily sensations-- I also just do that for about 5 to 15 seconds. And
I don't count specifically. Just kind of, roughly, 5 to 15 seconds.
© 2023 Scicomm Media LLC
9
OK, so second station, you're looking at the surface of your hand. And if you like, you can
also concentrate on your breathing. But typically, people would just focus on some
specific location on their hand.
Then I'll typically lower my hand, then I'll look off into the distance, maybe 5 to 10 feet.
Doesn't really matter. Focus my visual attention there. Try and hold that focus for 5 to 15
seconds.
Then I'll look further off in the distance, maybe further still off into the distance.
Ultimately, what I try and do is look at a location as far off in the distance-- into the
distance-- excuse me-- as I possibly can. And I'm also trying to pay attention to my
breathing at the same time, just as a way of calibrating my location to the location that
I'm looking at and how great that is.
Then, typically, I'll close my eyes and return my attention to my immediate environment
and my breathing, just in the location I'm in. So the entire thing only takes about two
minutes. Again, starting with eyes closed, focusing on self, 5 to 15 seconds, then eyes
open, focusing on surface of one's body, that is focusing one's visual attention, 5 to 15
seconds, maybe 10 feet away, then maybe 50 away, if you're in the metric system,
meters, folks, works just as well. These distances do not have to be precise-- and then,
off to the horizon, and then back to one's immediate location by closing one's eyes.
Now, what is happening when one does this perceptual exercise? And again, it's a
perceptual exercise. It's a visual perceptual exercise. Well, what's happening is you are
shifting your visual focus, obviously.
But you're also shifting the way in which you fine-slice or thick-slice time. Now, your
ability to recognize consciously, whether or not your thin-slicing or thick-slicing time, is
much harder to get a grasp of than it is to get a grasp of, whether or not you're looking at
your hand, or often in the distance. That's kind of obvious.
But what we know for sure is that as you shift your attention from your immediate
environment, out to different designated locations in your environment, and your time
perception shifts accordingly, you're essentially training your brain to shift visual focus
and the way in which you process in the time domain. And this is important in the
context of task-switching, because so much of task-switching is not just to understand,
OK, I'm going from reading to running, or from running to reading, and the different
types of operations that are required in one case versus the other, but also a shift in the
neural circuits that underlie your perception of time.
And again, this is a topic that deserves a much more elaborate discussion. But so much
of our ability to execute a task with high proficiency has to do with getting our thinking
and our actions into the correct time domain. Now, when I say "time domain," I know a
© 2023 Scicomm Media LLC
10
number of people can get confused, because time is time, right? People think, what do
you mean by time domain?
Space domain makes sense. Here, I'm not talking about outer space. Whether or not
you're looking in one location or another, close to your body or far away from your body
or different domains of space-- but the time domain is a little trickier for most people to
understand.
So just think of it this way. When you see a slow motion movie, what you're seeing is a
movie that was shot at a high frame rate, many frames per second. OK? The typical
smartphone shoots movies at about 60 frames per second, some older ones 30 frames
per second, the slow-mo function on your smartphone is actually a high-frame-rate
function.
You took the same movie, but you took it at a higher frame rate. So you've got a lot more
images. Therefore, you can generate slow motion. So with your visual system, when you
focus very close in to your body, or you're focused on bodily sensations in your
immediate environment, you are fine-slicing in the time domain, more so than when you
are looking further off in the distance.
Similarly, when you engage in one type of task, like a board meeting or a Zoom meeting
or a conversation with friends, you are in a very different set of neural circuit functions
than when you sit down to read or learn math or lift weights or go to therapy or go for a
walk with your dog, for instance. Now, it should be clear why when you move from task A
to task B, you want to, A, introduce a transition period.
It can be very brief. Maybe you don't even have time for the two-minute transition period.
You just say, OK, I'm in a transition period between task A and task B. I'm moving from
this thing to that thing. I just need, like, 10 seconds.
I'm going to recognize, I'm going to count down 10 to 1, or 1 up to 10. Doesn't matter.
This is transition time. But this is not a time to look at my phone or to be in lots of
different time domains.
Now, you might say, well, does that mean I shouldn't look at the horizon while I'm
walking from my meeting back to my desk? No. No, no, no. That's not the way that your
brain works. It doesn't anchor to things that just happen to be in your environment,
unless they're of particular interest.
What I'm saying is set a transition period between tasks-- ideally, 2, maybe as long as 10
minutes. I'm also saying that when you switch between tasks, or when you initiate your
first major task of the day, please expect, do expect, a period in which it's hard to get
into the groove, so to speak.
© 2023 Scicomm Media LLC
11
And in addition to that, I recommend having some of practice-- and I described the
practice that I've used for some period of time now, at least for me, to great success-where you are deliberately shifting your visual attention between different locations close
to you and far away, and you're doing that as a perceptual practice. Again, the whole
thing only takes about two minutes, maybe three minutes.
And you don't even need to do it every day. I happen to do it every day, but I miss the
occasional day here and there. And even if you were to do this perceptual practice once a
week or three times a week, I'm certain that you'll benefit.
Because in doing that perceptual practice, there's also an immediate recognition of the
sorts of shifts that your brain is required to engage in any time you move from task A to
task B or from task B to task C. And you start to see and feel-- literally, see and feel-- the
way that transition occurs, and that it takes a little bit of time, but that you can
accelerate that transition, if you understand that, oh, when I'm looking here and engaging
in this type of behavior or sets of tasks, and then I'm now going to be expected to do
another task in a completely different type of environment, that the brain is going to be
required to shift over the neural circuits that are active and less active in order to do
that, but that you can accelerate that process by practicing it, using that perceptual tool
that I described.
So there, I covered some specific tools that one can use to enhance one's ability to taskswitch, touching on a bit of the underlying neurobiology and why transition periods are
useful, if not required. If you think about it, there's always a transition period when task
switching. But here, you're taking conscious control over that transition period.
There are additional tools for enhancing one's ability to task-switch. They tend to be
somewhat specific for the certain kinds of cognitive or physical tasks that one needs to
do. The example of chess-boxing that I gave earlier-- a great example of task switching at
its extreme, terrible example of a practice space-time bridging.
Very safe. I can't think of any way in which it might be dangerous, although please don't
do it while driving or while operating any other machinery-- but by all accounts, very safe,
zero cost, and we talked about some of the other tools for task switching as well.
Our next question is about brain fog. And the particular question is, what can I do in
order to avoid getting brain fog? And what can I do when I have brain fog and I want to
shut it off? OK, well, this is an excellent question, because a lot of people struggle with
brain fog.
But we need to define what brain fog is, because there are a lot of reasons why one can
feel like they might have brain fog. But we're going to be better off answering this
question if we define what brain fog is from a bit of a physiological standpoint. And while
© 2023 Scicomm Media LLC
12
there isn't one single operational definition for brain fog-- by the way, an operational
definition is a definition that most or everyone in a given field agrees upon.
I think it's fair to say that when people talk about brain fog, they're talking about an
inability to concentrate, and it's often accompanied by sleepiness, daytime sleepiness in
particular. So we can define brain fog as a major challenge, because indeed, many
people report having brain fog, and some people, in fact, suffer from chronic brain fog.
Whenever it is they try and focus on something for sake of learning or just focus their
attention on even a conversation, their mind starts to drift. And it's important to point out
that brain fog is distinct from the symptoms of ADHD, Attention Deficit Hyperactivity
Disorder. And while, certainly, people who have ADHD can also suffer from brain fog, the
two things, or rather their symptomology, is thought to be distinct.
We can quickly deal with the distinction between ADHD symptomology and brain fog by
saying that the symptomology of ADHD most often-- not always, but most often-- is
associated with elevated levels of arousal but difficulty guiding one's attention and
keeping one's attention on a given task, especially tasks that one is not that excited
about. Right? Keep this in mind-- people with ADHD can maintain high levels of attention,
but typically, those high levels of attention are restricted to activities or topics that they
are very interested in or excited about, but it's the other stuff that they really have
challenges with.
Now, the typical presentation of brain fog is that it is not associated with high levels of
arousal that are creating difficulties in maintaining attention. Rather, it's as if one is in a
bit of a cloud, or fog, as the name implies, that has one feeling like they're being sort of
pulled under, that their levels of arousal are actually very low or are diminishing when
they try and focus. So somebody will sit down to read or write or learn something or pay
attention to a conversation or a lecture, and it's as if they're being pulled under.
Their levels of autonomic arousal are going down. OK? So that's one of the key
distinctions between ADHD and brain fog-- is with ADHD, elevated levels of autonomic
arousal-- typically, not always-- and with brain fog-- typically, not always-- lower levels of
autonomic arousal, or even downward-trending levels of autonomic arousal. And
autonomic arousal is the way that we refer to levels of energy, but in more physiological
terms. OK.
So the question was, what can one do to avoid getting brain fog, and what can one do to
deal with brain fog to eliminate it when one has it? OK, so let's talk about what one can
do to avoid getting brain fog. In answering a question like this, we have to first
acknowledge that there are going to be direct ways of avoiding brain fog, and there are
going to be indirect ways of avoiding brain fog. What do I mean by that? Direct ways of
dealing with anything, biologically, psychologically, et cetera, means tapping into the
very mechanisms that create the thing that you're trying to avoid. OK?
© 2023 Scicomm Media LLC
13
Indirect approaches are the things that set the landscape for or the opportunity to deal
with something. So oftentimes, on the podcast, I will distinguish between factors that
mediate a given process that are involved directly in a process, versus factors that
modulate a process. And the example I always give is the same one I'll give you now,
which is, if there were to be an alarm in the building that I happen to be podcasting from
right now, my attention would shift. My level of alertness would shift.
But we don't say that building alarms actually mediate levels of attention and arousal.
Rather, they can modulate levels of attention and arousal. The factors that mediate levels
of attention and arousal are things like epinephrine, norepinephrine, the amount of
activity in particular brain circuits, et cetera. And of course, we devote a lot of time and
attention to talk about those mediating mechanisms on the Huberman Lab podcast.
OK. So if we want to talk about what can one do to avoid getting brain fog, we need to
first think about modulating the indirect factors. And the big one here is going to be,
avoid poor or insufficient amounts of sleep. OK, it's sort of a "duh."
And it's a "duh," because all of us are familiar with the feeling of having not been rested
enough, or had a night's sleep that just was kind of a toss-and-turn night, or a night's
sleep that follows a particularly stressful psychological event, where you go to sleep and
you're asleep, but you're dealing with something, you're grappling-- you might even be
going through these little micro arousals or wakings throughout the night, and you sort of
know you are. You wake up in the morning, and you know that the state that you're in
when you wake up is very different than the one you were in throughout the night, but
you just don't feel rested.
You don't feel that deep sense of rest, that get-up-and-go that hopefully arrives within the
minutes or at least hour after you wake up. OK, so you have to get a great night's sleep if
you want to be able to pay attention and to avoid brain fog in your daily cognitive and
physical activities-- indeed, all activities. So I've covered the topic of sleep on a good
number of Huberman Lab podcasts.
And I'll refer you to just a few resources in our podcast site that can really help you
improve the quality and duration of your sleep. These things, by the way, are all
accessible at zero cost. There's the "Master Your Sleep" podcast episode that I did a
couple of years ago that is still very popular.
Again, timestamps-- you can navigate to the tools, or you can hear about the science
underlying the tools and the tools. There's the "Perfect Your Sleep" episode. There's the
guest episode with sleep expert and neuroscientist Dr. Matthew Walker from UC
Berkeley, who also wrote the fabulous book why we sleep. And there is a zero-cost toolkit
for sleep that you can access by going to hubermanlab.com.
© 2023 Scicomm Media LLC
14
Simply go to the Menu function, scroll down to Newsletter, and sign up for the newsletter
by providing your email. By the way, we don't share your email with anybody. And you
can also see previous newsletters in the form of PDFs right there, including the "Toolkit
for Sleep."
"Toolkit for Sleep" and those other episodes describes the things that you should really
do each and every day and night in order to ensure the best possible night's sleep. And
I'll just highlight a few of those now, but really, the resources I just described are the
place to go to get the full extent of the tools. The most important thing for getting a great
night's sleep is going to be the thing I always talk about, which is to get sunlight in your
eyes, or if you don't have access to sunlight, bright light in your eyes in the first hours
after waking.
Ideally, as soon as you wake up, you get sunlight into your eyes. But depending on time
of year location, et cetera, you might not be able to do that. But as soon as you possibly
can get at least 10 to 15 minutes of sunlight in your eyes early in the day, and if you
don't have access to sunlight for whatever reason, try and get some bright light in your
eyes.
You don't necessarily have to purchase a daylight simulator. Those can be very
expensive. But if you need to, you certainly can. We don't have any relationship to any
SAD lights, as they're called, or any SAD light vendors.
You can also get a 900-lux LED light that you can purchase at fairly low cost online.
Again, I have no relationship to any of those light sources, financially or otherwise. But
those are good ways to get light in your eyes-- that is, bright light in your eyes-- if you
don't have access to sunlight.
But-- and this is a very important point-- there is really no artificial source that compares
to the quality and effect of getting sunlight in your eyes early in the day, especially within
that first hour or two after waking, and doing that on a consistent basis. That's the key.
Do it on a consistent basis.
And all the details of how to do that-- for instance, you don't want to wear sunglasses or
do it through a windshield or through a window. It's fine to wear glasses, corrective
lenses, that is, or eyeglasses. However, how long to do it, the importance of blinking to
protect your eyes, all of that is included in the "Toolkit for Sleep" and the episodes of the
Huberman Lab podcast I refer to.
So that's the biggie for getting a great night's sleep. The other biggie for getting a great
night's sleep is to avoid drinking caffeine after 2 or 3 PM, and certainly within the eight
hours, and ideally, within the 12 hours before bedtime. And I know, I know, I know that
everybody says they can drink caffeine and then fall asleep without any trouble, but the
© 2023 Scicomm Media LLC
15
architecture of that sleep is not going to be as good as it would be if you avoided caffeine
in the eight, and ideally, 10 or 12 hours before you go to sleep.
So you want to avoid that caffeine as you're heading into the second half of your day,
certainly, and maybe even a little bit earlier. And the third thing, which is really a biggie
for getting the best possible night's sleep, is to avoid bright-light exposure between the
hours of 10:00 PM and 4:00 AM. If you wake up in the middle of the night and you need
to go to the restroom or something, try and use dim lights.
Try and especially avoid overhead, bright lights. If you absolutely have to look at your
phone in the middle of the night, really dim it down or get rid of all the blue light. There's
a feature that allows you to do that and that I'll talk about in an Instagram post coming
up soon.
But basically, you want to avoid bright-light exposure to your eyes as the nighttime is
approaching. And of course, for reasons related to parties and going out, for reasons
related to medical emergencies, or things that you have to do between the hours of
10:00 PM and 4:00 AM, there will be nights when you view bright light between 10:00
PM and 4:00 AM.
I hope that's for good reasons, not bad or emergency reasons. But don't obsess over the
fact that you looked at a little bit of bright light in the middle of the night or you had a
night out. That's not the point here.
The point is that you want to be as consistent as possible about the bright-light exposure
early in the day, about avoiding caffeine within 8, 10, maybe even 12 hours prior to
bedtime, and avoiding bright-light exposure to your eyes between the hours of 10:00 PM
and 4:00 AM on most nights. You have to live your life. These things aren't possible to do
all the time.
But those are the biggies. And then, the rest of the items, which are also biggies but I
don't have time to go into in depth here, are contained within the resources that I talked
about earlier. OK, so the reason I went on this riff about sleep and the importance of
getting sleep is that if you are not sleeping well, you can't really say you have brain fog
per se.
Most likely, what's happening is that there are indirect reasons related to the known
effects of sleep deprivation on cognition and focus and attention that are causing
excessive daytime sleepiness and what you're referring to as brain fog. But it is an
indirect modulatory-- in this case, negative-- force on your ability to concentrate. It's
creating brain fog.
So put quite simply, the big one for avoiding getting brain fog is going to be to make sure
that you're getting the best possible night's sleep on a consistent basis. Now, with that
said, there are some biological mechanisms-- in particular, neural circuit and
© 2023 Scicomm Media LLC
16
neurochemical-based mechanisms-- that are associated with brain fog. So these are
things like diminished levels of the so-called catecholamines, dopamine, norepinephrine,
and epinephrine, which are released both in the brain and body, that when are present at
diminished levels, that levels are too low, you're going to experience something like brain
fog.
And that's because of the role of these catecholamines in both arousal and in attention,
as well as learning, for that matter. Now, there are a variety of things that you can do to
increase the catecholamines and offset brain fog. And these span the typical array of
options when thinking about how to tap into your biology, or for that matter, your
psychology in any way.
There are behavioral tools, meaning do's as well as don'ts. There are nutritional tools,
including do's and don'ts. There are supplement-based tools, and of course, there are
pharmaceutical-based tools, prescription drugs. So as far as behavioral tools go, we can
divide it into two actionable categories.
The first is going to be intense effort, in particular, exercise effort. So we know that
intense exercise, in particular, exercise that takes place over a fairly short duration of
time-- so as little as five minutes, but extending out to about 45 minutes-- is going to
increase the catecholamines, dopamine, norepinephrine, and epinephrine quite
considerably, and leads to a fairly long-lasting increase in alertness and attention. Now,
the typical forms of intense exercise that people employ when they're trying to increase
catecholamines, and in doing so, also feelings of well-being, but at least in part to
increase their levels of attention, that sort of feeling of feeling good all day, or I felt better
after I trained.
High-intensity exercise pertains to resistance training. So this can be done with
bodyweight machines or free weights or some combination of those. It could also refer to
sprint intervals. And we did an entire series on different forms of exercise with Dr. Andy
Galpin. You can find that also at hubermanlab.com.
We also have a toolkit in the toolkit newsletter that I mentioned a bit earlier that details
the exercise regimen that I follow, that includes both intense training as well as longerdistance-- let's just call it low-intensity training, cardiovascular training and so forth. So if
you want details on how to do this type of training, you can find that there, again, at
completely zero cost.
But intense exercise is going to be exercise where you're really taxing your cardiovascular
and/or musculoskeletal system. So in the context of resistance training, this could take
the form of circuit training, but more typically, it's going to take the form of sets and
repetitions of resistance exercise, where you're pushing either to failure-- that is, an
inability to move the weight or your body for another repetition in good form-- or close to
that.
© 2023 Scicomm Media LLC
17
And as a consequence, you're going to be quite out of breath, at least at the end of those
sets, or for cardiovascular-type training, it's going to be more of the interval or highintensity interval training, or simply high-intensity training, that are going to get your
heart rate elevated to about 80% of maximum, or approximately 80% of maximum. It
could be 75, could be 85, or even higher, 90. The sorts of exercise that you decide to
employ, whether or not it's sprinting or cycling or rowing, is going to depend on what you
can do safely, that is without injuring yourself.
I always say, whatever exercise you're doing, whether or not it's resistance training, or
whether or not it's cardiovascular training, you need to pick movements that you can do
at a given intensity without harming yourself, so that you can come back and do more
exercise, ideally, the next day and the next day. OK, so this is why I don't say run. This is
why I don't say cycle.
This is why I say, I like to run and lift weights as my form of exercise, but some people
really don't like to or can't run. For me, the rower might be a good substitute, but I don't
like cycling, at least not on a road bike, for reasons that are very particular to me, but
you might love that. OK?
So we're not talking about the specific movements that one does. We're talking about
elevating one's heart rate to about 80% of maximum-- maybe a bit more, maybe a bit
less-- and doing that for a period of about 12 minutes, out to maybe even 45 minutes if
you're talking about something like resistance training, in order to get those heart rate
increases. Now, of course, resistance training isn't done specifically to elevate your heart
rate. It's done more typically, I should say, to generate some sort of adaptation response
of increased strength, increased hypertrophy, or some combination of those.
Now, in thinking about using exercise, either cardiovascular or resistance training to
decrease brain fog, or even to increase levels of attention, it's very important to
understand that when you do high-intensity interval training or high-intensity training of
any kind with weights or just with your body while running, any category of high-intensity
training, the total duration of that high-intensity training sets the stage for how you're
going to feel afterwards, meaning in the minutes, but also hours afterwards.
And here's the important thing to remember. If you do high-intensity training, say, in the
early morning hours-- this is when I prefer to do it if I can-- or sometime before noon,
what many people will find is if they keep that high-intensity training rather brief, so
anywhere from 12 to 45 minutes, maybe 50 minutes, maybe, maybe, maybe 60 minutes,
if you're extremely well-rested from the night before, then typically, you will maintain
higher levels of focus, and indeed, lower levels of brain fog throughout the entire day.
And then, of course, as evening approaches, it's natural to feel more sleepy. Hopefully,
you're dimming the lights and you're getting a great night's sleep to recover from your
exercise, and also rewire your brain according to all the things you were trying to learn
© 2023 Scicomm Media LLC
18
that dance. Because keep in mind that you actually learn while you sleep. That is, you
trigger learning while you're awake, but you actually rewire your brain connections while
you sleep, or in another form of deep rest called non-sleep deep rest.
So the point here is that if those high-intensity training sessions are done before noon,
let's say, so early in the day, and they are restricted in their total duration-- so let's set
the restriction for the total duration, just for sake of discussion here, at about 50 to 55
minutes for resistance training, and at about 30 minutes for high-intensity cardiovascular
training. Because frankly, I don't know many people who can maintain 45 or 60 minutes
of high-intensity cardiovascular training and still call it high-intensity training.
And this has to do with the inverse relationship between intensity and duration, and the
fact that when you do resistance training over the course of an hour, all of that resistance
training can be very high-intensity, because you have rest intervals in between that are
quite lengthy, where typically, your heart rate returns to baseline or at least close to
baseline. OK, so the point here, or the very specific takeaway, is that if your high-intensity
training is kept of short duration, it will tend to offset brain fog.
However, if your resistance training is of high-intensity and you're extending into the 75
minutes of high-intensity training, again, with resistance-- so body weights, machines,
free weights, and so on-- or, for instance, you see people in the gym or you know people
who will do a full 90 minutes or two hours of high intensity resistance training, well,
oftentimes what that will do is that will reduce total oxygen uptake by the brain in the
period that follows that high-intensity training.
And this is something I covered in a previous episode of the podcast. It's also something
that came up in that discussion that I did on the series on exercise science and
physiology with Dr. Andy Galpin. If you train very intensely early in the day, that's great.
It can give you a terrific physical and cognitive lift throughout the day.
But if that training session is too long-- again, we're cutting the threshold at about an
hour for resistance training and about 30 minutes for, again, high-intensity
cardiovascular training-- for some individuals, maybe 45 minutes of high-intensity
cardiovascular interval training that could get away with that, and then not have that
brain fog and crash throughout the day. But most people, if they're training really hard
early during the day and that extends too long, well, then they're going to experience
brain fog later in the day.
So this behavioral suggestion is sort of a two-pronged suggestion. There's a do, and
there's a don't. The don't is, don't train intensely for too long early in the day, and then
expect your brain to function really well throughout the day.
And this is something that I don't believe is discussed nearly enough. Because we hear
exercise is great for us, and indeed, it is. We hear that we need to do a combination of
© 2023 Scicomm Media LLC
19
low-intensity and more moderate- and high-intensity exercise, which indeed is true. But
what we don't hear is that if you do high-intensity training that's too long in duration, it's
going to divert fuel-based resources, but more importantly, oxygen-based resources away
from the brain and toward the body.
And anyone that's ever done a high-intensity 90-minute leg workout that included squats
and/or deadlifts and a bunch of other movements, and did a lot of sets, and left the gym
feeling like you left it all in the gym, knows what I'm talking about. So if you think about
it, what I just described includes both a do and a do-not related to brain fog. And it's
purely behavioral.
Now, there are some simpler-- and frankly, faster-- things that you can do using only
behavior in order to offset brain fog by way of increasing the catecholamines. And the
one that I come back to over and over again on the Huberman Lab podcast, not because
it's trendy, not because I think that it's the be-all-end-all, and certainly not because I
think it's a replacement for exercise or anything else, is deliberate cold exposure.
Deliberate cold exposure in the form of a cold shower or a plunge in a cold plunge of any
kind with ice or just with cold water, or in a natural body of water where-- please be safe,
by the way, folks. Never do any high-intensity breathing in combination with exposure to
cold water. Please don't do that. People have been injured, and indeed, people have died
doing that.
But just getting into cold water for 30 seconds to 2 minutes, maybe as long as 3 minutes
if you're cold-water-adapted and you have some experience doing it-- if done safely, and
there is a safe way to do this that I'll describe in a moment, is known to produce very fast
and very long-lasting increases in the catecholamines-- in particular, norepinephrine and
dopamine. And this is one of those behavioral tools where, at least if you're me, it does
not feel good while you're doing it.
Frankly, a lot of times, it doesn't even feel good before you get into the cold shower or
the cold bath, or the ice bath or the cold lake or the cold swimming pool. But afterwards,
I and most people find that they feel much better, much more alert, both alert and calm-elevated levels of attention, elevated motivation to focus on things that they want to learn
and do throughout the day.
And so deliberate cold exposure is a very potent tool that is very distinct in its time
course from high-intensity exercise. So it's something that you can do, and the range of
costs for doing deliberate cold exposure is pretty enormous. Let's take the lowest level of
cost. In fact, it's something that will save you money, and that's a cold shower.
If you are taking a cold shower as opposed to a hot shower, well, then you are going to
offset the heating bill. And I'm somebody who likes to end with warm or hot water after a
© 2023 Scicomm Media LLC
20
cold shower. Some people like to end with cold. Be my guest to do one or the other,
depending on your preference.
People who are trying to increase their metabolism typically will end with cold. There's
some debate as to how much deliberate cold exposure increases your metabolism. We're
not talking about metabolism here. We're talking about increasing your level of
catecholamines to offset brain fog.
Next up, the ladder on level of cost would be a ice bath where you're purchasing ice to
put in the ice bath. Believe it or not, that can be fairly expensive. To get enough ice into
an ice bath, that might cost you $40 or $50 in bags of ice, which, depending on your
disposable income, may seem like a trivial amount or, I think, for most people, it's kind
of a considerable amount.
So that's sort of the next level, but it's going to be a one-time thing. Once that ice melts,
you can't use it, obviously. And you would have to purchase it again to do deliberate cold
exposure.
The other approach, of course, would be if you have access to an ocean or a lake nearby.
That can be zero cost, depending on what it costs to access that ocean or lake. And then,
of course, there are commercial cold plunges. These are the ones that often get the most
attention, and these are typically in the range of anywhere from $3,000 up to $25,000.
And that's where I think at least part of the criticism of deliberate cold exposure comes
from. Oh, this is an attempt to just sell these fancy apparati of cold plunges. Keep in
mind, you can always do the cold shower option. Is it as good as a cold plunge? Is it as
good as an ice bath?
There are probably some minor differences. I think the consistency of doing the activity
here is more important than the actual device that you use, whether or not it's a cold
shower versus a cold plunge. And of course, then there's an even more expensive way to
do all this, which is cryo, right? So there's a machine that can deliver very cold
environment to you right up to the neck.
It is a much higher cost than an ice bath, but of course, unless you own one of these
devices, which are very, very expensive, you have to pay each time you do it, typically.
And so what I've just offered to you is an array of actually zero-cost to negative-cost-- can
reduce your heating bill-- to fairly high-cost ways to do deliberate cold exposure.
Again, I just want to say that deliberate cold exposure is but one tool to increase
catecholamines, but it is a very potent tool to do that. Will it completely offset brain fog?
Will it cure your brain fog? Certainly not. But if you're somebody who has very severe and
chronic brain fog, doing deliberate cold exposure ought to offset at least a portion of that
brain fog.
© 2023 Scicomm Media LLC
21
That said, for some people that have extreme brain fog, even deliberate cold exposure,
even resistance training done intensely, or cardiovascular training done intensely, is not
going to be sufficient to offset that brain fog. Now, as I go toward different types of tools,
not just behavioral tools that can offset brain fog, we have to keep in mind some of the
things that might actually be promoting brain fog. And here, there are a few interesting
surprises.
One of the surprises, at least to me, is a body of research focusing on how excessive
levels of capsule-based probiotics can increase brain fog. I know this is debated, but I'd
be remiss if I didn't at least share with you the idea that's out there that you can look into
further, and that perhaps we'll do an entire episode about on the podcast in the future, if
the literature on this fleshes out a bit more.
The point here is that probiotics, and prebiotics for that matter, are great. In particular,
prebiotic fiber-- in particular, getting probiotics from the foods you eat-- low-sugar
fermented foods being the best source of prebiotic fiber and probiotics-- so things like
kimchi, things like sauerkraut, things like pickles-- provided that the kimchi, sauerkraut,
and pickles are of the sort that need to be maintained in the refrigerator, and that they
are low-sugar varieties.
There's also things like kefir, things like kombucha. Again, the low-sugar varieties, things
that need to be maintained in the refrigerator, are going to be the one that contains
these live active cultures that are going to promote the proliferation of the healthy gut
microbiota. This is a topic that I covered previously on the Huberman Lab podcast, both
in terms of the mechanisms and the tools associated with those mechanisms, entitled
"Gut Health."
There's also an episode of the Huberman Lab podcast that I did with expert guest, my
colleague at Stanford School of Medicine, Dr. Justin Sonnenburg, that tapped into some
of these tools, and certainly, a lot of mechanisms as well. And in both episodes, we really
highlighted the fact that one of the best ways to ensure a healthy gut microbiome-- and
we now know that gut health is oh-so-important and the gut microbiome is one of the
best ways to support gut health-- is through the regular, that is daily, consumption of
low-sugar fermented foods of the sort that I just described. And there are a few others
that you can learn about in those episodes.
So probiotics and prebiotics and prebiotic fiber in the form of low-sugar fermented foods
and these other sources referred to in those episodes is extremely important and does
not-- I really want to emphasize-- is not going to and does not contribute to brain fog.
However, capsule-form probiotics, while they do have their place-- OK, I want to be very
clear here-- they do have their place at helping to reestablish a healthy gut microbiome,
especially after one has taken probiotics or when one is in a dysbiotic state, where they
have a depleted microbiome-- this could be anything from chemotherapy, all the way to
© 2023 Scicomm Media LLC
22
excessive travel and jet lag, or you're dealing with some other sort of immune insult in
the form of a flu or infection of any kind-- there is a place for capsule probiotics.
However, most of the time, if people are ingesting those low-sugar fermented foods on a
regular basis, and perhaps you're getting a little bit of extra probiotic or prebiotic from a
supplement like Athletic Greens, AG1, and of course, there are other supplements out
there that contain probiotics but at fairly low levels, right? These aren't very high levels of
probiotics that are present in Greens drinks and things of that sort.
Or you're drinking kombucha, or you're drinking kefir, or both-- you're going to be in that
safe range, where you're not going to create brain fog. However, there is this growing
idea that when people take excessive levels of probiotics in capsule form, in
supplementation form, that it actually can increase brain fog. Now, you might say, why
would that be?
This is because the gut microbiome is involved in creating the chemical milieu and the
very chemicals that are in the synthesis pathways for things like serotonin and for GABA-that is, for neurotransmitters and neuromodulators that impact our level of attention and
alertness. So again, I want to be very clear. I'm not saying that capsule probiotics are
necessarily bad.
In fact, there are times when I will take a capsule probiotic to just really buffer my gut
microbiome, if I've been taking antibiotics for whatever reason or I have been sick for
whatever reason, and I'm trying to really replenish my gut microbiome or ensure that it
stays in a healthy state. But most of the time, you want to avoid capsule probiotics,
unless, of course, your physician recommends them to you.
So the most important person to be hearing the message that I'm giving right now is the
person who is suffering from brain fog, who might already be taking high doses of
probiotics or probiotics in capsule form on a regular basis. You might want to take a look
at that. Definitely talk to your doctor before you add or remove anything from your
nutrition or supplement regimen.
And of course, for most people, please, please, please do take your gut microbiome
seriously. Reinforce that gut microbiome through the ingestion of whole foods that
include fibrous foods-- I'm a big believer in that-- as well as low-sugar fermented foods.
I'm also a big believer in that, based on the science that's been discussed on this
podcast. And frankly, it's been discussed elsewhere fairly extensively as well.
And if you need to rely on supplementation to further buffer your gut microbiome, well,
then a foundational nutritional supplement such as AG1-- and of course, there are others
out there. AG1 just happens to be the one that I'm most familiar with, because I've been
taking it for, gosh, nearly 12 years now. And it's one that I'm very familiar with, but of
course, there are others out there.
© 2023 Scicomm Media LLC
23
And I really want to emphasize this-- there is certainly no reason why you need to
supplement probiotics or prebiotics if you're being especially careful to get those from
the types of foods that we talked about earlier. My other suggestion for people that suffer
from brain fog is to at least consider the emerging literature on creatine. And when we
hear the word creatine, most people think, oh, creatine, that's about building bigger
muscles.
And indeed, if you take creatine-- and by the way, the most effective form of creatine
also, fortunately, turns out to be the most cost-effective form of creatine, which is
creatine monohydrate. And the typical dosage for creatine monohydrate is going to be 5
to 10 grams per day. You often hear 5 grams per day, but if you're a larger individual and
you look at the research, what you realize is that the typical dosage in the research is
going to be based on body weight.
So for me, I'm about 220 pounds, about 100 kilograms, so I take 10 grams of creatine
monohydrate per day. If you weigh less than I do, maybe half as much as I do, then 5
grams should be sufficient. You could also just take 5 grams a day consistently, because
there's a sort of a load-in phase that, in the old days, it was suggested that people take
high doses, like 20 or 30 grams per day, and then back off to a lower dosage.
But we now know that you can simply take a low dosage of creatine monohydrate each
day, and over time, you will load the creatine into your muscles, and some other tissues
as well, that I'll talk about in a minute. And indeed, there is a benefit to your muscles, to
your strength, and to your power output that is quite robust and supported in the
literature. And that's because that creatine is going to draw additional water stores into
the muscles. It's also going to contribute to some of the actual function of the muscle
fibers themselves.
This was covered in the exercise science series with Dr. Andy Galpin, so you can learn all
about the mechanisms there if you like. Now, creatine monohydrate, despite being an
effective tool for increasing muscular size, has also been studied extensively-- in fact, has
been studied far more extensively for its clinical roles-- in particular, its ability to
increase creatine phosphate stores in the brain. And your brain, like your muscles, relies
on multiple different fuel sources, depending on the activities that it's engaged in. -The point here is that when you take 5 grams, or maybe 10 grams of creatine per day,
you're going to increase the-- I don't want to say activity, but you're going to increase the
opportunity for the creatine phosphate system in the brain to be active. All right? There's
a much bigger conversation to be had there. I'm avoiding a lot of nuance right now for
sake of time. I'll return to this at a later time.
But there is fairly good evidence now that creatine supplementation has a cognitive
enhancing role. Now, this has been most extensively studied in the context of things that
also challenge the cognitive system, so in the context of sleep deprivation. So for
© 2023 Scicomm Media LLC
24
instance, creatine supplementation may be effective in offsetting some of the cognitive
deficiencies associated with mild sleep deprivation.
Creatine supplementation may also be effective in offsetting some of the cognitive
deficits associated with altitude-- or novel altitude, because some people are adapted to
altitude. Creatine supplementation has now also been shown to offset some of the
fatigue, both cognitive and physical fatigue, associated with infections-- in particular,
viral infections that occurred even months earlier. So there was a recent study that got a
lot of attention in the press that I'll just briefly mention and you can go check it out,
which is entitled "The effects of six-month creatine supplementation on patient- and
clinician-reported outcomes, and tissue creatine levels in patients with post-COVID-19
fatigue syndrome."
Post-COVID-19 fatigue syndrome is a syndrome where people feel, as the name suggests,
a lot of mental and physical fatigue. And for some people, it's mild, and for some people,
it is both very long-lasting and very severe. And this was a small study, I want to
emphasize. This was a small study-- only 12 patients with post-COVID-19 fatigue
syndrome, who took 4 grams of creatine monohydrate per day.
And the researchers were able to see that creatine stores increased, both in particular
muscles as well as within particular brain areas. So this is called white matter brain
areas. White matter is where the myelinated, the fatty ensheathed fibers of neurons that
we call axons and the myelin that allows for high-speed transmission between neurons
that governs, essentially, every function, cognitive, and physical-- the point being that in
this study-- here, I'm quoting from the study, by the way-- "taking creatine for six months
appears to improve tissue bioenergetics--" so basically, referring to the availability of
creatinine in the muscle and brain-- "and to attenuate clinical features of post-COVID-19
fatigue syndrome."
So the creatine supplementation, by the way, compared to placebo, manifested in a
significant improvement in levels of attention, levels of arousal, and kind of readiness to
perform mental or physical work, this kind of thing. We will provide a link to this study so
you can parse it in more detail. Again, it's a small study, but an intriguing one. And it
makes a lot of sense, frankly, that creatine supplementation might offset some of this
post-COVID-19 fatigue that some people experience.
Because there's already a fairly extensive literature on creatine supplementation
increasing brain, creatine phosphate stores, and improving cognition. So I think that
creatine is an interesting and, certainly, a fairly low-cost approach if one wants to think
about adding supplementation as a way to offset or even combat brain fog. So as I
mentioned earlier, there are behavioral, there are nutrition-based, and there are
supplementation-based tools to offset brain fog.
© 2023 Scicomm Media LLC
25
I just talked about, mainly, behavioral, but also some supplementation-based
approaches. I didn't talk too much about nutrition, although, keep in mind what I said
earlier about low-sugar fermented foods if we're keeping a healthy gut microbiome. So I
think everyone agrees that ideally, most people are consuming mostly minimally
processed or non-processed foods, really trying to avoid highly processed foods.
But if we are thinking about offsetting brain fog, we have to also understand that any
time you eat any food, even if it's the healthiest food in the world, whatever that means to
you, but that probably means non-processed or minimally processed-- and that's true
whether or not you're a vegan, or you're following the carnivore diet, or you're an
omnivore like me. Well, if you consume very high volumes of any food, whether or not it's
ribeye steaks or apples, you're going to divert a lot of blood to your gut, and you are
probably going to feel a bit fatigued, including a bit mental-fatigued.
So people rather obsess about which foods are going to increase alertness. And we've
talked before on the podcast about how certain foods contain more l-tyrosine, which is an
amino acid precursor, to dopamine. We've talked about foods that contain choline, which
is a precursor, ultimately, to acetylcholine, which is a neuromodulator associated with
attention.
And one can come away from a discussion like that or from other discussions about the
relationship between food neurotransmitters and the role of neurotransmitters and
alertness in the brain, and think, oh, I should eat certain foods and I'll feel more alert.
And while that is sort of true, it's equally, if not more, important to remember that if you
eat a large volume of any food, no matter what amino acids it contains, you're going to
feel fatigued afterwards, because of the fact that you're going to divert a lot of bodily
resources to digesting that food and clearing that food from the gut.
So the point here is that whatever foods you eat, you have to be mindful of the fact that if
you eat excessive volume of those foods, you are going to feel sleepy. You're going to
have what a lot of people think of as brain fog. And this is not a trivial point, because I
think a lot of people think, oh, you know, I wake up, I slept well, I have my coffee, then I
have my workday, I maybe worked out early in the day, then I eat my lunch, and then I
feel really sleepy, and I have brain fog in the afternoon.
These are often the people that are relying on caffeine later in the day, which, again, I
don't suggest. And for these types of people-- and by the way, this represents billions of
people on our planet-- there are a couple of recommendations I can point to that are
often very effective, such as delaying your caffeine intake by about 90 to 120 minutes
after waking-- which, by the way, folks, I never said everyone needs to do.
What I've said-- and I'll continue to say-- is that for people that struggle with a
pronounced dip in energy in the afternoon, so-called afternoon crash, even though they're
sleeping well at night, that delaying your caffeine intake to 90 to 120 minutes after
© 2023 Scicomm Media LLC
26
waking can often offset the afternoon crash. OK? I never said everyone should delay their
caffeine intake by 90 to 120 minutes after waking. However, a lot of people that delay
their caffeine for 90 to 120 minutes after waking find they have much more sustained
energy levels throughout the morning and throughout the day.
OK. So that's point number one. The second is that for people that eat a very large lunch,
you're going to feel sleepy afterwards-- or I should say, most people will feel very sleepy.
The one exception might be if you exercised hard early in the day, hopefully not too
intensely for too long, per our earlier discussion, well, then you might require a fairly
large meal, or at least a fairly calorie-dense meal.
But if you put a large volume of food in your gut, whatever the caloric density, whatever
the foods happen to be, it is entirely expected that you will have brain fog or a dip in both
mental and physical energy at some period of time after doing that. So keep the meal
sizes, not necessarily small, but make sure that those meal sizes are not excessive.
Now, the last point I want to make about offsetting brain fog goes back to
supplementation and a little bit into prescription drugs. There is a fairly large category of
supplements that some people refer to as nootropics, a word that I absolutely despise,
because it means smart drugs, and frankly, there is no circuit in the brain for being
smart. There are circuits in the brain for different types of mental operations.
But these are things that have shown some ability, some effectiveness, in elevating levels
of alertness-- things like Alpha-GPC, which essentially serves as a precursor to
acetylcholine, or l-tyrosine, the amino acid precursor to dopamine. Now, it's been argued
that supplements like Alpha-GPC and l-tyrosine are not efficiently converted into the
neuromodulator targets that they are claimed to be-- so things like acetylcholine and
dopamine.
However, there's a decent body of literature to at least show that Alpha-GPC, when taken
at dosages of 3 to 600 milligrams, maybe even as high as 900 milligrams for people that
tolerate it very well, or people that take anywhere from 500 to 1,500 milligrams-- OK? I'm
saying milligrams of l-tyrosine-- experience elevated levels of alertness. And in some
studies, you can find evidence for increased level of attention, combating mental fatigue,
and even improved cognition, although the cognition one is really where the data are
particularly lacking.
And this is where we have to separate increased levels of alertness and ability to
maintain attention from actual increased cognition or ability to perform certain cognitive
operations. OK? So that's why I don't like that word, nootropic, because it lumps all of
those things together. Nonetheless, there is evidence that Alpha-GPC, l-tyrosine, taken
alone or together, sometimes in combination with caffeine, can increase levels of
attention and alertness that are favorable for offsetting brain fog.
© 2023 Scicomm Media LLC
27
However, I don't think people should rely exclusively on these tools. Nowadays, I also
hear about people taking paracetamol and huperzine. Huperzine increases acetylcholine
a bit more potently and through a different pathway than Alpha-GPC, and so on and so
forth.
I know that as soon as we get into a discussion about this, the tendency is to think, oh,
either he's-- meaning me-- is simply suggesting supplements to offset brain fog. And
certainly, that's not the case. You need to pay attention to the behavioral tools, the
nutrition tools, the sleep-based items that I talked about earlier, before even considering
supplementation.
But I think there's also the kind of reflexive response that a different group of people
have, where they think, oh, these are supplements that cure brain fog, and that's not
true. They operate in a context of how well-rested you are, whether or not you're
caffeinated or not, whether or not you are cognitively interested in the material that
you're trying to learn, and so on and so forth. So that's important to remember.
Now, in terms of prescription drugs to offset brain fog, there is the entire category of
prescription drugs that, frankly, are both used for the treatment of ADHD, as well as
abused, mainly on college campuses, but by people in the tech industry, the finance
industry-- frankly, all industries-- for elevating levels of attention and focus for long
periods of time. These are drugs, such as Ritalin, Vyvanse, Adderall, and others.
Again, as I pointed out in the episode on ADHD, those drugs can be very effective for
certain people, both young and old, in treating ADHD, clinically diagnosed ADHD. They
are not for everybody, but they are effective for a good number of people. So we don't
want to demonize them in every case, but they are not for everyone.
Here, we're talking about brain fog in particular. And in terms of the ability for that
category of drugs to offset brain fog, they do have efficacy. But typically, when people are
taking those drugs to offset brain fog, we're not talking about offsetting the symptoms of
ADHD, and therefore, we are talking about either off-label or illegal use of those drugs,
which is not something-- certainly, the illegal use of those drugs is not something that I
condone.
Off-label use-- well, that's something that you need to discuss with your doctor. There is a
category of prescription drug that is definitely worth noting in the context of this
conversation about brain fog that has been explored-- that is, there are good research
and clinical data for the ability of this drug, or category of drugs, rather, to increase
levels of focus and attention as well as cognition, especially under conditions of sleep
deprivation, and in some conditions, brain fog as well.
And these are the drugs most typically known as modafinil and armodafinil, sometimes
also referred to as Provigil, and they go by other names as well. Modafinil, Provigil, has
© 2023 Scicomm Media LLC
28
been shown over and over again to increase cognitive ability when people are sleepdeprived, and more and more physicians are also now prescribing it for treatment of
brain fog. One thing about modafinil, Provigil, is that it tends to be very expensive, or at
least it used to be, which is why armodafinil was created.
Armodafinil is a lower-cost version of modafinil. Some people will argue that it's not as
effective as modafinil. The clinical literature argued that it is as effective as modafinil,
despite its lower cost.
That's something that really needs to be sorted out between you and your prescribing
physician. And I want to underline, highlight, and boldface "prescribing physician,"
because I am not a fan of, nor am I condoning, people taking modafinil or armodafinil for
brain fog without working with a physician. In fact, any time you're going to take a
prescription drug or remove a prescription drug from your regimen, or anytime you're
going to add a supplement or remove a supplement from your regimen, it is advisable
that you consult with a physician.
So I just told you about a wide range of tools for offsetting brain fog, maybe even for
treating brain fog. Those were, make sure you get excellent sleep, OK? I know it's hard to
do. It involves a number of different steps. We talked about those steps earlier and the
resources for learning more about those steps.
Talked about doing high-intensity training, ideally early in the day, and making sure that
the high-intensity training is not of duration that's too long, that then you divert fuel
sources away from your brain and you have brain fog. We also talked about deliberate
cold exposure and why it is effective in increasing alertness, and can potentially offset
brain fog. We talked about it in its different forms and the cost of those different forms,
including negative cost for a cold shower.
I keep coming back to deliberate cold exposure. And here, by the way, I should mention
that we've also done a toolkit newsletter about deliberate cold exposure. Again, just go to
hubermanlab.com, go to the Menu, scroll down to Newsletter, sign up for the newsletter,
and you can access that deliberate cold exposure protocol-- again, all at zero cost to you.
And then, we also talked about maintaining a healthy gut microbiome as being essential,
but not taking excessive levels of capsule probiotics, because that itself may increase
brain fog. We also talked about supplements like Alpha-GPC, l-tyrosine, piracetam,
which, again, are not going to be the ideal first approach to dealing with brain fog, but
provided you're doing everything else that we talked about, may be a good secondary or
tertiary approach if you're still experiencing some brain fog.
And we talked about some prescription drug approaches that are gaining popularity.
Those were modafinil and armodafinil, often called Provigil and Nuvigil. And here, just
like with supplements, I don't think that prescription drugs should be the first approach,
© 2023 Scicomm Media LLC
29
but they do often have a place for certain people who are doing all the things correctly
behaviorally, in terms of do's and don'ts. They're eating correctly. They're not overeating.
They're eating the right foods. They're doing their exercise, maybe even supplementing
with the sorts of things we talked about a moment ago, and they're still experiencing
brain fog. In those cases, one might consider the prescription drugs.
And then, forgive me, I forgot to mention just now in my list, but earlier, we also talked
about the fairly limited amount of data, but the mechanistically logical data, about
creatine and offsetting brain fog, and in some cases, offsetting mental and physical
fatigue in post-COVID-19 syndrome.
I'd like to take this time to thank you for joining me for this Ask Me Anything episode.
And I'd like to thank you for being a premium subscriber to the Huberman Lab podcast.
I'd like to remind you that if I haven't answered your question already, that I will be doing
these Ask Me Anythings every month. I will continue to sift through the questions that are
on the Premium website, and I would encourage you to put additional questions there
and to upvote questions that you'd like to see the answers to.
If any of the questions that I responded to today you didn't feel were thoroughly
answered enough, then please add a new question there and point that out. I will read all
the questions that are there, and I will strive to answer them as thoroughly, concisely,
and clearly as possible. Again, you can put those at hubermanlab.com/premium. And as
always, thank you for your interest in science.
[MUSIC PLAYING]
© 2023 Scicomm Media LLC
30