Chapter 14 - Sleep, Dreaming and circadian Rhytms Flashcards
Rapid eye movement (REM)
- associated with stage 1 EEG
- loss of core-muscle tone
- low amplitude, high-freqeuncy
What are three standard psychophysiological bases for defining the stages of sleep?
- Electroencephalogram (EEG)
- Electrooculogram (EOG)
- Electromyogram (EMG)
Just before sleep
- alpha waves : waxing and waning bursts of 8-12 Hz EEG waves (low-voltage, high-frequency)
First-night phenomenon
when in a sleeping lab, you must be there for several nights before starting with the analysis, because you might sleep different in the first night.
Stage 1 sleep EEG
- low-voltage, high-frequency
- similar but a but slower than alert wakefulness
Stage 2 sleep EEG
- higher amplitude and lower freqeuncy
Which two characteristic wave forms appear in stage 2 Sleep EEG?
- K complex: single large neagtive wave (upward deflection) followed by a single large posiitve wave (downward deflection)
- Sleep spindle: 0.5 to3 sec waxing and waning burtsts of 9 - 15 Hz waves.
Stage 3 sleep EEG
- predominance of delta waves (largest and slowest EEg waves)
Initial stage 1 EGG (1) vs. Emergent stage 1 EGG (2)
- first period of stage 1 EEG during a night’s sleep
- subseqeunt stage of stage 1 sleep EEG, accompanied by REMs and by a loss of tone in muscles of the body core.
NREM sleep
- all other stages together
- inital stage 1, stage 2, stage 3
What are 5 beliefs about dreaming? And are they correct?
- External stimuli can be incorporated into dreams (TRUE)
- Dreams only last an instant -, dreams run in real time
- Some poeple claim they they don’t dream - BUT thse peopel have as much REM sleep as normal dreamers.
- Penile erections - indicative of dreams with sexual behavior? -NO, even babies have them.
- Poeple belief that sleep talking and sleepwalking occur in REM sleep - NO true.
Interpretation of dreams - Sigmund Freud
- dreams represent unacceptable wishes
- key to understand people - interpret the manifest dreams (dreams we experience)
Activation-synthesis hypothesis
- based on observation that, during REM sleep, many brain-stem circuits become active and bombard the cerebral cortext with neural signals
- info is random and that the resulting dream in the cortex is effort to make sense out of these random signals.
Why do we sleep, and why do we sleep when we do - two kind of theories …
- Recuperation theories of sleep
- Adaptation theories of sleep
Recuperation theories of sleep
being awake disrupts the homeostasis (internal physiological stability) of the body and sleep is required to restore it.
Two most common theories of the recuperation theory …
- Restore energy levels (that decline during wakefulness)
- Clear toxins (that accumulate during wakefulness)
Adaptation theories of sleep
sleep is not a reaction to the disruptive effects of being awake but the result of an internal 24-hour timing mechanims.
Comparative analysis of sleep - Investigation of sleep has led to several important conclusions:
- Sleep serves important physiological function
- The primary function of sleep is not special, higher-order human function
- Sleep is not necessarily needed in large quantities.
- No strong relation between a species sleep time and its level of activity, body size or temperature
Predictions of recuperation theories about sleep deprivation
- Long periods of wakefulness will produce physiological and behavioral disturbances
- These disturbances will grow worse as the sleep deprivation continues.
- After a period of deprivation has ended, much of the misses sleep will be regained.
Moderate amounts of sleep deprivation have been foud to have three consistent effects:
- Sleep-deprived individuals display an increase in sleepiness
- Sleep-deprived individuals display negative affect on various written tests of mood.
- They perform poorly on test of sustained attention.
Microsleeps
breif periods of sleep, typically 2 - 3 seconds long
Carousal appartaus
used to deprive an experimental rat of sleep while a yoked rat is exposed to the same number and pattern of disk rotation
REM sleep deprivation has shown two major effects:
- REM rebound
- Participants have to be awakened more often - greater tendency for participants to initiate REM sequences (with each sucessive night of deprivation)
Default theory of REM sleep
it is difficult to stay continously in NREM sleep, so the brain periodically swithces to one of the two other states (REM sleep and wakefulness)
6 major pieces of evidence that sleep deprivation increases the efficiency of sleep
- People regain most of their slow-wave sleep
- After sleep deprovation: slow-wave sleep is characterized by an even higher proportion of slow-waves
- People sleep 6 hours or less per night get as much slow-wave sleep (as people sleeping 8 hours)
- Taking a nap after waking up . naptime EEG shows fewer slow waves
- Reducing sleep time leas to less NREM 1 &2 (but same amount of NREM 3)
- Waking people during NREM 3 - major effects on the sleepiness.
Zeitgebers
environemntal cues (light-dark cycle) that can entrain the circadian rhythms
Free-running rhytms
circadian rhytms in constant environemnts with no zeitgebers