Biological Rhythms
a. types of biological rhythms
b. neurohormones
Sleep
a. functions of sleep
b. measuring sleep
c. dreaming
d. neural mechanisms
e. sleep disorders
Biological Rhythms
a. types of biological rhythms
b. neurohormones
Sleep
a. functions of sleep
b. measuring sleep
c. dreaming
d. neural mechanisms
e. sleep disorders
Biological rhythms
1. Circannual
2. Infradian
3. Circadian (Latin: Circa = “around”, dian = “day”)
– Zeitgeber: “time giver”
– Entrainment: alignment of rhythm with external cues
e.g., suprachiasmatic nucleus and sunlight
Biological Rhythms
a. types of biological rhythms
b. neurohormones
Sleep
a. functions of sleep
b. measuring sleep
c. dreaming
d. neural mechanisms
e. sleep disorders
Biological Clocks
– Suprachiasmatic nucleus
• A nucleus situated atop the optic chiasm responsible for
organizing circadian rhythms.
– Pineal gland
• A gland attached to the dorsal tectum; produces melatonin and
plays a role in circadian and seasonal rhythms.
Suprachiasmatic Nucleus
– Part of hypothalamus
– Damage disrupts
rhythm.
Retinohypothalamic pathway
Pineal Gland
– Rene Decartes Treatise of man
(1640)- “principal seat of the
rational soul”
– releases melatonin (at night)
– melatonin is derived from
serotonin
Biological Rhythms
a. types of biological rhythms
b. neurohormones
Sleep
a. functions of sleep
b. measuring sleep
c. dreaming
d. neural mechanisms
e. sleep disorders
Functions of sleep
• Universal phenomenon among vertebrates.
• Only warm-blooded vertebrates (mammals and birds) exhibit
REM sleep.
• Essential to survival.
• Improves memory.
• Conserve energy resources.
• Recuperate physically.
Sleep Deprivation
• Restorative effects of sleep appear to be more important
for brain than rest of body.
• Deprivation does not appear to interfere with ability to
perform physical exercise.
• Cognitive abilities can affected by sleep deprivation.
• Brain rests during slow-wave sleep.
• Mental activity during the day increases slow-wave
sleep at night.
Rebound phenomenon
• REM sleep increases after a period of REM sleep
deprivation.
Biological Rhythms
a. types of biological rhythms
b. neurohormones
Sleep
a. functions of sleep
b. measuring sleep
c. dreaming
d. neural mechanisms
e. sleep disorders
EEG
1. Frequency of the wave (n of peaks/unit time)
– tells you about the number of cortical
neurons generating EPSPs
2. Amplitude of the wave (height of wave)
– tells us about the n of EPSPs that occur at the same
point in time
– n of neurons firing in synchrony
EEG Wave Types
– Alpha activity
• A smooth electrical activity of 8–12 Hz recorded from
the brain; associated with relaxation.
– Beta activity
• Irregular electrical activity of 13–30 Hz recorded from
the brain; associated with arousal.
– Theta activity
• EEG activity of 3.5-7.5 Hz that occurs intermittently during early
stages of slow-wave and REM sleep.
– Delta activity
• Regular, synchronous electrical activity of less than
4 Hz recorded from the brain; occurs during deep sleep.
Stages of Sleep
– REM sleep
• Desynchronized EEG activity during sleep; associated with
dreaming, rapid eye movements, and muscular paralysis.
– Non-REM sleep
• All stages of sleep except REM sleep.
– Slow-wave sleep
• Non-REM sleep, characterized by synchronized EEG activity
during deeper stages.
Copyright © 2008
Pearson Allyn & Bacon
25
Characteristics of REM sleep
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low amplitude, high frequency desynchronous EEG
rapid eye movement (REM)
lower species show more REM sleep, as do human infants
narrative dreams
muscle atonia
– motor cortex active but descending motor pathways paralyzed
• penile erections and vaginal secretions
• deepest stage?
– incorporate things into our dreams
– more likely to spontaneously awaken
Biological Rhythms
a. types of biological rhythms
b. neurohormones
Sleep
a. functions of sleep
b. measuring sleep
c. dreaming
d. neural mechanisms
e. sleep disorders
Sigmund Freud (1900) Interpretation of Dreams
water = birth
flying = sexual arousal
knifes, swords = castration anxiety
mud = feces
cave, hallway = mother
Dream theories
– Freud
• Repressed memories and expression of libido.
– Activation synthesis theory
• Sensory experiences are fabricated by the cortex as a means
of interpreting signals from the PGO activity.
– Continual activation theory
• Encoding of short term procedural memories into long-term
memories.
Biological Rhythms
a. types of biological rhythms
b. neurohormones
Sleep
a. functions of sleep
b. measuring sleep
c. dreaming
d. neural mechanisms
e. sleep disorders
Sleep is not a passive process
Cerveau isole
• mesencephalon transection
• continuous sleep
Encephale isole
• brainstem transection
• permanent insomnia
Sleep/Waking “Flip-Flop”
vlPOA= ventrolateral preoptic area
ACh = acetylcholine
NE = norepinephrine
5-HT = serotonin
Ventrolateral Preoptic Area
GABA neurons
• Activation promotes sleep.
• Destruction results in total insomnia.
Locus Coeruleus
Norepinephrine neurons
• Located in the pons near the rostral end of the floor of the
fourth ventricle.
• Involved in arousal and vigilance.
• Decreased activity during sleep (both slow-wave and REM)
Locus coeruleus
– Acetylcholine
• Cholinergic neurons located in the pons and basal
forebrain produce activation and cortical desynchrony.
– Serotonin (5-HT)
• Appears to play a role in activating behavior.
– Histamine
• Neurotransmitter that increases wakefulness and arousal;
found in tuberomammillary nucleus of hypothalamus, just
rostral to mammillary bodies.
– Hypocretin (orexin)
• A peptide produced by neurons whose cell bodies are
located in the hypothalamus and project to arousal
mechanisms; destruction causes narcolepsy.
Neural control of REM sleep
– PGO wave (pontine, geniculate, occipital):
• Bursts of phasic electrical activity originating in the pons,
followed by activity in the lateral geniculate nucleus and
visual cortex.
– Peribrachial area
• The region in the pons; contains acetylcholinergic neurons
involved in the initiation of REM sleep.
Peribrachial area
IC = inferior colliculus
PPT = pedunculopontine
tegmental n.
LDT = lateral dorsal tegmentum
Biological Rhythms
a. types of biological rhythms
b. neurohormones
Sleep
a. functions of sleep
b. measuring sleep
c. dreaming
d. neural mechanisms
e. sleep disorders
Sleep Disorders
– Insomnia
• Affect approximately 25% of the population
• No single definition of insomnia
• May be a symptom of physical ailment.
– Sleep apnea
• Cessation of breathing while sleeping.
• Can be mediated centrally or locally (obstructive).
• May play a role in sudden infant death syndrome.
– Narcolepsy
• Disorder characterized by periods of irresistible sleep, attacks
of cataplexy, sleep paralysis, and hypnagogic hallucinations.
• Treat with stimulant medications.
– Cataplexy
• Paralysis during waking.
– Sleep paralysis
• Paralysis just before a person falls asleep.
– Hypnagogic hallucination
• Vivid dreams that occur just before a person falls asleep;
accompanied by sleep paralysis.
– Nocturnal enuresis
• Bedwetting
– Somnambulism
• Sleepwalking
– Pavor nocturnus
• Night terrors
Insomnia vs. Sleep Deprivation
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27-year-old clinical psychologist on internship
Gets up at 6:30 AM
Works and mothers all day
Goes to bed about midnight
She gets about 6.5 hr sleep per night
Insomnia vs. Sleep Deprivation
• 58-year-old woman, who is married and whose
husband has retired
• Gets up at 8:30 AM
• Goes to church, reads, plays bridge
• Goes to bed about 10:00 PM
-sleeps until 1:30 AM
-is “up and down” rest of night
-finally gets out of bed around 8:30 AM
• She gets about 6.5 hr sleep per night
Insomnia vs. Sleep Deprivation
• Insomnia assumes adequate opportunity to
sleep.
• Sleep Deprivation
-adequate ability to sleep
-inadequate opportunity
-generally sleepy, at risk for accidents
• Insomnia
-inadequate ability to sleep
-adequate opportunity
-generally not sleepy, though may report
fatigue
Definitions of Insomnia
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Difficulty falling asleep
Difficulty maintaining sleep
Waking up too early
Nonrestorative or poor-quality sleep
May have daytime impact
Insomnia
primary cause - sleep medications
- develop tolerance; REM rebound
- we are poor estimators of how much sleep we get.
treatments
- Medications in short term
- CBT in long term
• 8-10 wks to change poor habits and beliefs
• sleep restriction, stimulus control, relaxation
techniques, and education.
• unfortunately, takes time and few practitioners
Medications
• Use of hypnotics increased 60% from 2000 to
2006, at a cost of $45 billion per year.
FDA-Approved Medications
• Benzodiazepines
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estazolam (Prosom)
flurazepam (Dalmane)
quazepam (Doral)
temazepam (Restoril)
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triazolam (Halcion)
• Benzodiazepine Agonists
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eszopiclone (Lunesta)
zaleplon (Sonata)
zolpidem (Ambien)
• Melatonin Agonists
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ramelteon (Rozerem)