task 6 Flashcards
The three standard psychophysiological bases for defining sleep in stages
- electrocehalogram (EEG)
- electrooculogam (EOG)
- electromyogram (EMG)
first-night phenomenon
the disturbance of seep observed during the first night in a sleep laboratory.
there are…. stages if sleep
4
just before sleep (as seen on a EEG)
- alpha waves : waxing and waning bursts of 8-13 Gz
stage 1
- low voltage, high frequency (slower than that of alert wakefulness)
- also called REM sleep
- loss of cire-muscle tone
- ceberal activity (bloodflow, neuron firing) increases till waking levels in many brainstructures
- general increase in the variability of the autonomic nervous system system (respiration, blood pressure)
- penile erection in males
stages 2
- gradual increase in voltage and decrease in frequency compared to stage 1
- K complex: a large negative wave (upwards), followed by a single large positive wave (downwards)
- sleep spindle: waxing and waning outbursts of 12-14 Hz waves
- NREM sleep (non-rem sleep)
stage 3
- gradual increase in voltage and decrease in frequency compared to stage 1 and 2
- occasional presence of delta waves
delta waves
the largest and slowest EEG waves, with a frequency of 1-2 Hz
stage 4
- gradual increase in voltage and decrease in frequency compared to the other stages
- a predominance of delta waves
initial stage 1 EEG
- first period of stage 1 EEG
- not marked striking EOG or EMG changes
emergent stage 1 EEG
- subsequent periods of stage 1 sleep EEG
- REMs
- loss of tone in the muscle of the body core
REM sleep
rapid eye movement
slow-wave sleep (SWS)
sleep 3 and 4 together ( =because of delta waves)
Freud on dreams
manifest dreams (sleep dreams) are merely disguised versions of our latent dreams (real dreams)
activation-synthesis theory
the information supplied by the cortex during REM sleep is largely random and that the resulting dream is the cortex’s effort to make sense of these random signals.
recuperation theories of sleep
being awake disrupts the homeostasis of the body in some way and sleep is required to restore it
adaptation theories of sleep
- sleep is the result of an internal 24-hour timing mechanism.
- To conserve energy resources and to be less susceptible to predation in the dark
- sleep is a behaviour we are highly motivated to engage in, but not necessary to stay healthy
the effects of sleep deprivation are often difficult to study because they are often cofounded by
stress
sleep deprivation leads to (3)
- increase in sleepiness
- worse performance on written tests of mood
- worse performance on tests of vigilance (computer screen responding)
sleep deprivation impacts which cognitive function
worse performance on tests of executive function
executive function
cognitive abilities that appear to depend on the prefrontal cortex. For example, innovative thinking, lateral thinking, assimilating new information to update plans and strategies.
physiological consequences of sleep deprivation
- reduced body temperature
- increased blood pressure
- decreases in some aspects of immune function
- hormonal changes
- metabolic changes
microsleeps
brief periods of sleep (2-3 seconds long) during which the eyelids drop and you become less responsive to external stimuli while your still standing or sitting
the carousel apparatus is used to
deprive an experimental rat of leep
REM sleep deprivation has two effects
- following REM sleep deprivation, someone display a REM rebound
- with each successive night of REM sleep deprivation, there is a greater tendency for participants to initiate REM sequences.
REM rebound
people will have more than usual amount of RE sleep for the first two nights after the REM sleep deprivation
mnemonic function
pertaining to memory
according to the default theory of REM sleep
- it is difficult to stay continuously in NREM sleep, so the brain periodically switches to one of the other two states.
- REM sleep and wakefulness are similar states
antidepressants reduce
REM sleep
sleep deprivation causes sleepers to become more efficient because
- sleep deprived have a higher proportion of slow-wave sleep, which is the main restorative function
circadian rhythms
rhythms lasting about a day
nocturnal animals
animals that sleep during the day and stay awake at night
zeitgebers
environmental cues, such as light-dark cycle, that can control the timing of the circadian rhythms
circadian rhythms are
- freerunning rhythms
- freerunning period
the biological clock habitually runs
-slow unless it is entrained by timerelated cues in the environment (25 hours instead of 24)
internal desynchronization
when subjects are housed in constant laboratory environments, their sleep-wake cycle and body temperature cycles sometimes break away from one another
jet lag occurs when
the zeitgebers that control the phases of various circadian rhythms are accelerated during west-bound flights (phase advances) or decelerated during east-bound flights ( phase delays)
what happens in shift work
the zeitgebers stay the same, but workers are forced to adjust their natural sleep-wake cyclus in order to meet the demands of their work schedule.
2 ways of reducing jet lag
- gradually shifting someone sleep-wake cycle in the days prior to the flight
- administering treatments after the flight that promote the required shift in the circadian rhythm
circadian clock
internal timing mechanism that by using physiological systems regulate sleep
suprachiasmatic nuclei
- SCN
- located in the medial hypothalamus
- disrupts circadian cycles therefore contains a circadian timing mechanism
There are minor circadian clocks in mammals for example
cells from other parts of the body display free-running circadian cycles of activity when maintained in tissue culture
