CH 14: Sleep, Dreaming, & Circadian Rhythms Flashcards
Describe the 3 standard physiological measures of sleep.
- EEG = Electroencephalogram
- Measure of gross electrical activity of the brain via scalp electrodes
- Some periods of high-voltage& slow EEG waves
- Some periods of low-voltage & fast EEG - EOG = Electrooculogram
- Measure of eye movement
- REM = rapid eye movements under closed eyelids of sleepers during periods of low-voltage, fast EEG activity - EMG = Electromyogram
- Measure of muscle tension
- Loss of electromyographic activity in neck during sleep periods
Describe the 3 stages of sleep EEG.
STAGE 1:
- Low voltage, high frequency signal
- Similar to but slower than alert wakefulness
STAGE 2:
- Slightly higher amplitude & lower frequency than stage 1
- Punctuated by 2 characteristic wave forms: K Complexes & Sleep Spindles
STAGE 3:
- Predominance of DELTA WAVES = largest & slowest EEG waves
–> Stays in stage 3 EEG sleep for some time then retreats back through stages of sleep to stage 1
–> Gradual increase in EEG voltage & decrease in EEG frequency as move from stage 1 through 2 and 3.
See Figure 14.2
Explain the difference b/w REM & non-REM sleep.
- REM Sleep = stage of sleep characterized by rapid eye movements, loss of core muscle tone, & emergent stage 1 EEG
vs.
- NREM Sleep = non-REM sleep = all other stages of sleep
Describe the relationship b/w REM sleep & dreaming.
List 1 evidence of support.
- Besides loss of tone in core muscles, all other measures suggested that REM sleep could be the physiological correlate of dreaming
- -> SUPPORT:
- 80% of awakenings from REM sleep led to dream real vs. 7% of awakenings from NREM sleep
Describe 5 common beliefs about dreaming & assess their validity.
- External stimuli can become incorporated into dreams (i.e. spraying water on face)
- Dreams last only an instant, but research shows dreams run on ‘real time’
- Some ppl claim not to dream, but these ppl have just as much REM sleep as normal dreamers
- Penile erections assumed to be indicative of dreams of sexual content
- -> But emotions are no more complete during dreams w/ sexual content than those w/o it - Sleep-talking & sleep-walking occur during REM sleep
- -> FALSE bc sleep-talking can occur during any stage, & sleep-walking occurs during slow-wave sleep (ie. not REM)
Describe the ACTIVATION-SYNTHESIS HYPOTHESIS.
Activation-Synthesis Hypothesis:
= Theory that the info supplied to the cortex by the brain stem during REM sleep is largely random & that the resulting dream is the cortex’s best effort to make sense of those random signals
- ie) Staring up at clouds & seeing faces
- -> Clouds are randomly patterned but brain trying to make sense of that pattern
List 2 kinds of theories of sleep.
- Recuperation Theories of Sleep
2. Adaptation Theories of Sleep
Describe the RECUPERATION Theories of Sleep.
- Being awake disrupts body’s homeostasis & the function of sleep is to restore it
- Implies that sleepiness is triggered by deviation from homeostasis caused by wakefulness, & that sleep is terminated by return to homeostasis
Describe the ADAPTATION Theories of Sleep.
- Sleep evolved to protect organisms from predation & accidents, & to conserve their E rather than to fulfill some particular pgnhysiologifcal need
- More focus on WHEN we need to sleep than on FUNCTION of sleep
Explain 4 conclusions that have resulted from the comparative analysis of sleep.
- Fact that most mammals & birds sleep suggests that sleep serves important physiological function
- -> Rather than protecting animals from mishap & conserving E
- -> SUPPORT = sp at ^risk of predation when sleep (i.e. antelope), & sp who evolved complex mech that enable sleep (i.e. dolphin sleep w/ half of brain so other half can regulate air) - Fact that most mammals & birds sleep suggests the primary function of sleep isn’t some special, higher-order human function
- The large between-species difference in sleep time suggest that although sleep is essential for survival, it’s not necessarily needed in large quantities
- No strong relationship b/w a species’ sleep time & its level of activity, its body size, or its temp
- ie) giant sloths sleep 20h/day = argument AGAINST theory that sleep is a compensatory reaction to E expenditures
Explain how stress can often be a confounding variable when considering the effects of sleep deprivation.
- Sleep-deprivation procedure itself can be stressful, even on healthy volunteers
- Must interpret results of sleep-deprivation studies w/ caution
- -> Bc hard to separate effects of sleep loss from effects of stressful conditions that may have induced sleep loss
- Ppl sleep deprived often bc illness, work shifts, exams, drugs, etc.
List the 3 assumptions that Recuperation Theories make about the effects of sleep deprivation.
- Long periods of wakefulness will produce physiological & behavioural disturbances
- These disturbances will grow worse as sleep deprivation continues
- After a period of deprivation has ended, much of the missed sleep will be regained
Describe 2 classic sleep-deprivation case studies.
- The Case of the Sleep-Deprived Students:
- Able to focus on studying until 3AM, stay away & able to function normally during morning, repeat
- Each night, got harder to stay awake, but morning after had decreased sleepiness
- -> Could perform normal tasks as long as remained active - The Case of Randy Gardner
- Broke world record of 260hrs of consecutive wakefulness
- On first night after, slept 14h, then back to usual 8hr schedule
Describe the major effects of sleep deprivation in humans (3).
- ^^sleepiness
- (-) affect on various written tests of mood
- Perform poorly on tests of sustained attention (i.e. watching for a moving light on comp)
List the physiological consequences of sleep deprivation in humans (5)
(But there’s little evidence that these changes have health/performance consequences)
- Reduced body temp
- ^bp
- Decreases in some immune function
- Hormonal changes
- Metabolic changes
Describe the CAROUSEL APPARATUS.
Provide a critique of the Carousel Apparatus as a method of sleep deprivation.
Carousel Apparatus:
= Deprives experimental rat of sleep while yoked control rat is exposed to same # & pattern of disk rotations
–> Disk on which both rats stand rotates every time the experimental rat displays sleep EEG
–> If the sleeping rat doesn’t awaken imm., it’s deposited the water
–> Exp. rat dies while control rat is healthy
–> May die not bc lack of sleep, but bc it’s stressful
Describe the effects of REM-sleep deprivation (2).
- Display REM REBOUND = have more than their usual amount of REM sleep for first 2-3 nights after REM-sleep deprivation
- w/ each successive night of deprivation, there’s ^tendency for participants to innate REM sequences
- -> as REM-sleep deprivation proceeds, they have to be awakened more & more frequently to keep them from accumulating sig amounts of REM Sleep
Describe the 6 pieces of evidence that less sleep is ass. w/ ^efficient sleep.
- Although ppl regain only small proportion of total lost sleep after period of sleep deprivation, they gain most of their lost slow-wave sleep
- After sleep deprivation, slow-wave EEG of human characterized by even higher proportion of slow waves than usual
- Ppl who sleep <6hr/night get as much slow-wave sleep as ppl who sleep >8hr
- If individual take a nap in morning after full night’s sleep, their nap time EEG shows few slow waves, & the nap doesn’t reduce duration of following night’s sleep
- Ppl who reduce their usual sleep time get less NREM 1 & NREM 2 sleep, but their duration of their slow0wave sleep remains same as before
- Repeatedly waking individual during REM sleep produce little increase in sleepiness they experience the next day
- -> Whereas repeatedly waking individuals during slow-wave sleep has major effects
