sleep, dreaming and circadian rhythms (3.1) Flashcards
physiological measures of sleep (3)
electroencephalogram (EEG): reveals gross electrical activity of the brain “brainwaves”
electrooculogram (EOG): records eye movements seen during rapid eye movement (REM) sleep
electromyogram (EMG): detects loss of activity in neck muscles during some sleep stages
awake
low-voltage, high-frequency (fast) waves; everything essentially independent from one another (every place doing its own thing)
pre-sleep
intermittent alpha waves (indicative of tiredness), bursts of low-frequency (8-12Hz) EEG waves
stages of sleep (4)
sleep: voltage increases and frequency decreases (slows) with progression
stage 1: theta waves (low-voltage, high-frequency; similar to, but slower than, awakeness)
stage 2: spindles and K complexes (indication that cortex has received stimuli that the thalamus could not make a decision on; stimulus not enough to wake you up)
stage 3: occasional delta waves (large and slow, 1-2Hz)
stage 4: predominantly delta waves
emergent stage 1 sleep
after initial stages; rapid eye movement (REM) sleep; dreams; loss of body core muscle tone (cerebral activity increases to awake levels)
dream interpretations (2)
troubled subconscious (Freud: unacceptable repressed wishes); activation-synthesis theory (DLPFAC decides “what” and makes a story out of it)
theories for sleep (2)
recuperation: sleep needed to restore homeostatic balance lost during the day
adaptation: sleep is the result of an internal timing mechanism, evolved to conserve energy and to protect us from the dangers of the night
comparative analysis of sleep theories (2)
not a special human function (all mammals and birds sleep); no clear relationship between species’ daily activity levels and sleep times (i.e. sloth)
support (2) and inconsistencies (3) with recuperation theory on sleep deprivation
support: bad mood, reduced cognitive abilities and sleepiness; reduced immune function, increased blood pressure, lower body temperature
inconsistencies: unimpaired logical and critical thinking; retained physical strength and motor performance; recovery sleep is relatively short
circadian rhythms
“lasting about a day”; internal clock
zeitgebers
environmental cues that entrain circadian cycles; “time givers” (i.e. light-dark cycle)
altered sleep-wake cycles (free-running, jet lag, shift work)
free-running circadian rhythms: without zeitgebers, rhythms governed by internal circadian clock (runs slow)
jet lag: zeitgebers accelerated (east) or decelerated (west)
shift work: zeitgebers unchanged, but sleep-wake cycle must be altered
suprachiasmatic nucleus (SCN)
located in hypothalamus; sleep-wake circadian clock; lesions periodically abolish sleep time
sleep-wake areas (4)
anterior hypothalamus (VLPO): sleep
posterior hypothalamus: wakeful
rostral reticular formation: wakeful
caudal reticular REM nuclei: sleep
drugs that affect sleep (3)
hypnotic: enhance the effect of the inhibitory neurotransmitter GABA in the brain; mode = depress wakeful centers; complication = tolerance
antihypnotic: increase activity of catecholamine transmitters by enhancing release and/or blocking reuptake; mode = activate sympathetic fight/flight NS; complications: lost appetite, addiction
chronobiotic: increase melatonin levels in the brain; mode = higher levels of melatonin prolong sleep
