Hypothalamuscontrols your biological clock, regulating changes in blood pressure,
body temperature, pulse, blood sugar levels, hormonal levels, activity levels, sleep, and
wakefulness over 24 hours in normal environment (25 hours in a place without normal
night–day).Circadian rhythms—daily patterns of changes.Reticular formation (reticular activating system)—neural network in brainstem
(medulla and pons) and midbrain essential to the regulation of sleep, wakefulness,
arousal, and attention.States of consciousness include: (normal waking) consciousness, daydreaming, sleep,
hypnosis, meditation, and drug-induced states.
Sleepis a complex combination of states of consciousness, each with its own level of
consciousness, awareness, responsiveness, and physiological arousal.
- Stage 1 sleep—quick sleep stage with gradual loss of responsiveness to outside,
drifting thoughts, and images (the hypnagogic state). EEGs show theta waves. - Stage 2 sleep—about 50% of sleep time. EEGs show high-frequency sleep spindles
and K-complexes. - Stage 3 sleep—deep sleep stage. EEGs show some high-amplitude, low-frequency
delta waves. - Stage 4 sleep—deepest sleep stage. EEGs show mostly delta waves. Slowed heart
rate and respiration, lowered temperature and lowered blood flow to the brain.
Growth hormone secreted. - REM sleep (Rapid Eye Movement sleep)—sleep stage when eyes dart about.
About 80% dreaming, 5 to 6 times each night (about 20% of sleep time). Called
paradoxical sleep because EEGs are similar to stage 1 and wakefulness, but we are
in deep sleep with skeletal muscles paralyzed. - NREM (Non-REM sleep)—sleep stages 1 through 4 without rapid eye movements.
During sleep we synthesize proteins and consolidate memories from the preceding day.Sleep disorders include insomnia,the inability to fall asleep and/or stay asleep; nar-
colepsy,sudden and uncontrollable lapse into sleep (usually REM); and sleep apnea,
temporary cessations of breathing that awaken the sufferer repeatedly during the night.
Sleep disruptions include night terrors,characterized by bloodcurdling screams and
intense fear in children during stage 4 sleep; and sleepwalking (somnambulism),usu-
ally in children during stage 4 sleep.
Three theories of what dreams mean:
- To [Freudian] psychoanalysts, dreams are a safety valve for unconscious desires.
Manifest content—according to Freud, the remembered story line of a dream.
Latent content—according to Freud, the underlying meaning of a dream. - Activation-synthesis theory—during REM sleep the brainstem stimulates the fore-
brain with random neural activity, which we interpret as a dream. - Cognitive information processing theory—dreams are the interplay of brain
waves and psychological functioning of interpretive parts of the mind.
Daydreaming—state with focus on inner, private realities, which can generate creative
ideas.
Hypnosis—state with deep relaxation and heightened suggestibility. The hidden
observer provides evidence for dissociation of consciousness.
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