Awake: alpha (awake, relaxed, drowsy, often with eyes closed, synchronized) and beta (alert, attentive, thinking, desynchronized) activity

Stage 1: alpha and theta activity, transition between sleep and wakefulness

Stage 2: theta activity, sleep spindles and K complexes (both involved in keeping person asleep by decreasing sensory awareness)

• at this point, the person is sleeping soundly, but if awakened, will deny having been asleep

• at this point, the person is in deep sleep; if awakened, acts groggy and confused

• nightmares may occur, but of awakened, will not report a story, but an emotionally-charged situation

• at this point, the person is easily aroused by meaningful stimuli; if awakened, appears alert and attentive

• dreaming, if awakened, will recite narrative-type story

• complete sleep cycle about 90 minutes long

• each cycle contains a 20-30 minute period of REM

• slow wave sleep occurs mostly during first half of nite

1) adaptive response

2) restorative process

PURPOSE OF REM SLEEP

1) learning - more REM after learning; impaired performance after learning if sleep deprived; less REM in retarded vs. normal children; more REM during exam time in college students

2) developmental - offspring of animals born with developed brains spend less time in REM than less developed offspring (Problem with this theory?)

SLEEP DISORDERS

1) insomnia - affects 20% of population at any given time (Definition?)

Causes:

• sleeping medications - drug dependency insomnia

• misreporting by patients causes frequent prescription

• limited affects of sleeping medications, anyway (fall asleep 15 minutes faster and sleep 30 minutes longer than without meds)

• pseudoinsomnia - dream that they are awake

• sleep apnea - airway obstruction; potentially lethal; episodes of stopped breathing last at least 10- seconds and occur more than 30 times a night; may use CPAP device - Continuous Positive Airway Pressure

• characterized by sleep attacks, with almost instantaneous onset of REM sleep

• about 10% of narcoleptics show all of the following associated features:

• cataplexy - momentary paralysis without loss of consciousness occurring in association with sudden emotional reactions

• sleep paralysis - occasionally episodes when patient cannot move, occurring just before or after sleep

• hypnagogic hallucinations - particularly vivid auditory or visual hallucinations

4) bedwetting - bell and pad treatment; typically occurs during slow wave sleep

5) sleepwalking - not related to dreaming, occurs in slow wave sleep

6) night terrors - child acts awake and terrified, but actually in slow wave sleep

BIOLOGICAL CLOCKS

1) circadian rhythm - a daily, rhythmical change in behavior or physiological process

• we have internal clocks and also respond to zeitgebers, which are environmental cues

• suprachiasmic nucleus (SCN) - in hypothalamus

• lesions in rats disrupt circadian rhythms, but not amount of sleep

• retina has direct projections to the SCN, as light (primary zeitgeber in most animals)

• individual neurons show rate of circadian rhythms in their action potentials and levels of Fos protein ("ticking" of biological clock)

3) daily schedule - anticipation of lunch, for example

4) seasonal rhythms - pineal gland secretes melatonin when directed to do so by the SCN

PHYSIOLOGICAL MECHANISMS OF SLEEP AND WAKING

Controlled by substances in blood promoting sleep or wakefulness?

Arousal - controlled by brainstem

• locus coeruleus in pons has widespread neurons which release norepinephrine, which are associated with vigilance (maintaining attention to external stimuli)

• acetylcholine and serotonin - also involved in arousal, mostly behavioral activation

• basal forebrain region; lesions in rats cause insomnia, leading to coma and death

• preoptic area - neurons involved in temperature regulation; warming of this area causes drowsiness and sleep

• may be mechanism designed to "cool" the brain periodically by suppressing behavior and lowering metabolic rate

• occurs when:

• PGO waves (pons, geniculate, occipital), first manifestations of sleep

• rapid eye movements

• cortical desynchrony

• muscular paralysis

• increased genital activity