An Outline of What You Really Need To Know

Introduction--Sleep occupies one third of our existence. It is actively generated by the discharge of specific neurons in certain parts of the brain. Sleep affects and in turn is affected by almost every physiological and psychological process. It is necessary for our mental and physical health. Disturbances of sleep result in a variety of debilitating sleep disorders; they also exacerbate other illnesses.

What sleep is--Sleep is a biological state consisting of non-rapid eye movement (NREM) sleep and rapid eye movement (REM) sleep.

The Sleep Cycle--NREM and REM sleep altemate cyclically throughout the night beginning with NREM sleep, which lasts about 80 minutes. NREM sleep is followed by REM sleep, which lasts about 10 minutes. This 90 minute cycle is repeated 3-6 times each night. In successive cycles the amount of NREM sleep decreases and the amount of REM sleep increases. Each state is comprised of a constellation of biological patterns of activity.

NREM TONIC REM PHASIC REM

EEG Stage 1--low voltage,
mixed frequency low voltage,
mixed frequency low voltage,
mixed frequency

Stage 2--low voltage, 12-14 Hz spindles

Stage 3--some delta (0.5-2 Hz) waves

Stage 4--predominantly delta waves

EOG slow rolling eye movements isolated rapid
eye movements clusters of rapid
eye movements

EMG moderate activity atonia in most
peripheral muscles atonia plus
myoclonic twitches

NREM (vs. Wakefullness) TONIC REM
(vs. NREM) PHASIC REM (vs. TONIC REM)

Cerebral activity decreases increases further increases

Heart rate slows about the same increases and is variable

Blood pressure decreases about the same increases and is variable

Cerebral blood flow no change increases further increases

Respiration decreases increases and is variable further increases and is variable

Airway resistance further increases increases and is variable increases and is variable

Penile tumescence infrequent oh yeh! oooh yeh!

Clitoral tumescence infrequent oh yeh! oooh yeh!

Hormones--Growth hormone is secreted during sleep early in the night. Prolactin secretion peaks later during sleep. Gonadotropin secretion occurs during sleep predominantly in puberty. Secretion of thyroid stimulating hormone peaks in the evening and is inhibited during sleep.

Phylogeny of Sleep Developmental Course of Sleep Dreams

All mammals have NREM and REM sleep. Small mammals sleep a lot (10-20 hours a day); most large mammals sleep less (5-10 hours a day). Birds have little NREM and REM sleep. Reptiles only show EEG signs of NREM sleep. Amphibians and fish have rest/activity cycles but exhibit neither NREM nor REM sleep. Newborns sleep 16-18 hours a day; young children about 10 hours; adolescents about 8 hours; adults 7-8 hours; elderly people 5-6 hours a day. 50% of newborn sleep is REM sleep; 20% of adult sleep is REM sleep. NREM sleep shows a steady decline in old age. Dreams occur during NREM and REM sleep; in both states they can be bizarre as well as mundane. It takes as long to dream a dream as it takes for the dream to occur in real life. Emotions in dreams reflect the dreamer's waking personality. Stimuli during wakefulness are not readily incorporated into dreams.

Brain Mechanlsms of Sleep and Wakefulness Chemical Mechanisms of
Sleep and Wakefulness Circadian Regulation of Sleep and Wakefulness

Wakefulness--depends principally on the functioning of reticular activating system in the brainstem. NREM Sleep--depends on the basal forebrain. REM Sleep--depends on the dorsolateral pontine tegmentum.
Wakefulness-- by cortical noradrenaline (and dopamine and acetylcholine) from terminals of brainstem neurons. NREM Sleep--maintained by GABA from basal forebrain neurons. REM Sleep--initiated by acetylcholine that activates pontine neurons. The timing of sleep, but not the amount, is regulated by a circadian clock in the suprachiasmatic nucleus. The clock runs a 25 hour day. It regulates many physiological processes which interact with sleep, such as temperature regulation.

Possible Functions of Sleep--
Restoration and Recovery: but we do not know what is restored or what is recovered.
Energy Conservation: but about the same amount of energy would be conserved by an animal resting quietly.
Prey-Predator: but who eats whom?
Memory Consolidation: sleep interferes with information received just Fior to sleep.
Various and Sundry Other Functions.
a. Brain Growth
b. Programming of Innate Behavior
c. Discharge of Emotions
d. etc., etc., and so forth

Sleep DISORDERS--

Narcolepsy-- a disturbance that is characterized by irresistible sleep attacks during the day. It consists of cataplexy, sleep paralysis and hypnagogic hallucinations.

REM Behavior Disorder-- occurs during REM sleep when there is a failure of the mechanisms that normally promote atonia.

Sleepwalking and Night Terrors-- occur during NREM sleep and are relatively benign.

Hypersomnia-- can be due to Obstructive Sleep Apnea.

When we don't get enough sleep, our body demands that it occur and psychologically we crave it more than chocolate chip cookies. If we don't get any sleep, we die (or feel as if we had). Sleep undoubtedly serves many vital functions, but what they are no one, except maybe the Shadow knows!

Proceed to Part N.

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	NREM	TONIC REM	PHASIC REM
EEG	Stage 1--low voltage, mixed frequency	low voltage, mixed frequency	low voltage, mixed frequency
	Stage 2--low voltage, 12-14 Hz spindles
	Stage 3--some delta (0.5-2 Hz) waves
	Stage 4--predominantly delta waves
EOG	slow rolling eye movements	isolated rapid eye movements	clusters of rapid eye movements
EMG	moderate activity	atonia in most peripheral muscles	atonia plus myoclonic twitches

	NREM (vs. Wakefullness)	TONIC REM (vs. NREM)	PHASIC REM (vs. TONIC REM)
Cerebral activity	decreases	increases	further increases
Heart rate	slows	about the same	increases and is variable
Blood pressure	decreases	about the same	increases and is variable
Cerebral blood flow	no change	increases	further increases
Respiration	decreases	increases and is variable	further increases and is variable
Airway resistance	further increases	increases and is variable	increases and is variable
Penile tumescence	infrequent	oh yeh!	oooh yeh!
Clitoral tumescence	infrequent	oh yeh!	oooh yeh!