SLEEP SCIENCE Hand-out
Benjamin Trnka, University of Chicago
SLEEP IN OUR SOCIETY
Sleep Deprivation is increasing around the US and around the world.
1 out of 2 teens know that they get less sleep than they need and are tired over the course of the day.
Only 1 out of 5 teens get the recommended 9 hours of sleep per night.
3 out of 5 teens report that they drink one caffeinated drink (coffee, soda, hot
chocolate, etc…) daily. And 33% drink 2 or more!
HOW DO WE MEASURE SLEEP?
EEG= Electroencephalography is used to identify the different stages of sleep,
measuring electrical activity of the brain across the scalp.
THE STAGES OF SLEEP
2 types: Rapid Eye Movement (REM) and Non Rapid Eye
Relaxed Wakefulness
Stage 1
Movement (NREM). We spend 75% of our time asleep in
NREM sleep which has 3 stages, and 25% of our time in
REM. We cycle through the stages about five times a night.
SLEEP DEBT
&
CIRCADIAN
RHYTHM
Stage 2
Theta Waves
Sleep Spindles
Stages 3
While
we’re awakewe build up a
Sleep Debt: for every hour awake, more than half an hour
Alpha Waves
K-Complex
Delta Sleep
REM (dream sleep)
needs to be paid off in sleep. Teenagers need 8.5-9.25 hours
of sleep each evening. Sleep requirements decrease over time
and differ from person to person.
Our Circadian Rhythm, also known as the
Wakefulness
Biological Clock is a day-long cycle of changes in hormones,
body temperature and other processes which make our body alert at certain times in the day.
Our sleep debt and circadian rhythm change throughout the day so that there are times when we are most alert
and times when we are most tired.
Biological-Clock Dependent Alerting
Sources: National Sleep Foundation Sleep “Myths and Facts,” “2006 Sleep in America Survey,” “Healthy Sleep Tips“
(www.sleepfoundation.org); Dr. Dement, The Promise of Sleep; Ferber and Kryger, Principles and Practice of Sleep Medicine in
the Child; Hobson, Sleep; Pressman and Orr, Understanding Sleep Psychology 106, UC Berkley OpenCourseWare, Lectures
2,3,4,8;
Neuroscience
Behavior, MIT OpenCourseWare, Lectures 23,24.
HOW DO
WE FALLand
ASLEEP?
Pineal Gland
The Suprachiasmatic Nucleus or SCN responds to light-exposure
and then sends signals to the Pineal Gland which then
releases Melatoninone of the main
hormones that starts the
sleep cycle.
SCN
Our circadian rhythms
*During puberty, melatonin
production
is decreased, which scientists
believe
delays circadian rhythms in teenagers.
can shift* according to
light and melatonin
exposure:
DREAMING: In REM sleep, the visual cortex, hypothalamus and limbic systems are activated,
generating experiences and emotions to create dream content. Less blood flow goes to the frontal lobe
(where are critical thinking is controlled), allowing us to believe even bizarre content in our dreams.
Active during dreaming
Inactive during dreaming
IMMUNE SYSTEM
WHAT IS SLEEP GOOD FOR ANYWAY?
Firstly, not sleeping has many negative effects: Tumor Necrosis Factor (TNF), a brain chemical that fights
illnesses from flu to cancer. It increases 10x during sleep!
HORMONES
Human Growth Hormone (HGH) is only released
in deep sleep! This is the hormone that builds
muscle, causes growth spurts and repairs cells.
Testosterone, Prolactin, Luteinizing Hormone & Follicle
Stimulating Hormone are also released.
MEMORY
With a full 8.5 hours of sleep within the first 24 hours after
learning, some studies show that people can have a 20%
increase in speed and 30% improvement in accuracy of their
memory. Other studies show a 40% increase in the efficiency of
(From the National Sleep
Foundation and Dr. Dement)
learning new things with good sleep the night before learning.
80% of students that get optimal sleep report getting As & Bs!
REMEMBER: Teenagers need 8.5-9.25 hours of sleep!
1. Pay off your sleep debt (40 minute naps are a great way to achieve this) and then maintain a
consistent sleep schedule (even over weekends and breaks)!
2. Make a regular and relaxing bedtime routine (listen to soothing music, read a book, etc…)
3. Make sure your sleep environment is dark, quiet, comfortable and cool.
4. Try to keep electronics out of your room! Not only do they emit light, but any items
that can cause anxiety should be taken out of your bedtime routine!
5. Finish exercising and eating at least 2 hours before sleep- both can make it harder to fall asleep.
6. Avoid caffeine (coffee, tea, soft drinks, chocolate, etc…) close to bedtime. It can keep you awake!
Keep track of your sleep habits with a sleep log and record when you sleep, for how long, and how awake you
feel during the day. Talk to your parents or a doctor if you are concerned about your sleep quality.