sleep Flashcards
(27 cards)
identify three ways of measuring sleep
1/ electro-encephalogram (EEG) - head
2/ electro-oculogram (EOC) - eye
3/ electro-myogram (EMG) - neck
outline the stages of sleep
pre-sleep
stage 1
stage 2
stage 3
stage 4
describe the electrical activity that occurs in pre-sleep
- alpha waves
- bursts of 8-12Hz of activity
- low amplitude
- high frequency
describe what happens in stage 1 of sleep
- amplitude starts to increase
- frequency starts slowing down
describe what happens in stage 2 of sleep
- sleep spindles
1-2 second quick bursts of 12-14Hz waves - K complex
sharp up and down deflection
describe what happens in stage 3 of sleep
- frequencies progressively slower
describe what happens in stage 4 of sleep
- very large amplitudes
how long does a sleep cycle last?
90 minutes
(from stage 1 - 4)
what is the first stage 1 called?
initial stage one
what are the subsequent stage 1’s called?
emergent stage 1
what is REM?
rapid eye movement
outline Dement (1978) findings into the stages of sleep
- found 80% of those that woke up during REM sleep can recall their dream
- found 93% of those that woke up during nREM = no dream recall
- nREM (slow wave sleep) could only recall isolated experiences of the dream
- REM dream could recall the narrative of the dream
identify 2 theories of sleep
1/ recuperation theories
2/ evolutionary theories
explain what recuperation theories of sleep are
- idea that being awake disrupts homeostasis
- when you sleep, homeostasis is restored
- e.g.: sleep restores energy levels
explain what evolutionary theories of sleep are
- idea that sleep has evolved in humans to prevent accidents and predation at night
- suggests that sleep is not needed but we are motivated to have it
does sleep depend on species size?
- no
- sleep is not related to body size/temperature
- it has been found that exercise has little/no effect on sleep duration in humans
(Youngstedt & Kline, 2006)
what theory of sleep is sleep in animals consistent with?
- not consistent with recuperation theory
- related to evolutionary theory
sleep in animals depends on two factors:
- how vulnerable you are asleep
- time spent eating during the day
how is sleep deprivation explained by recuperation theory?
- recuperation theory suggests that sleep deprivation increases physiological/behavioural disturbances
- after deprivation, theory suggests missed sleep must be regained
what did Cirelli (2006) find about sleep deprivation?
- found sleep deprivation influences mood, physiological function, molecular function
- consistent with recuperation theory as it demonstrates physiological/behavioural disturbances brought on by sleep deprivation
outline findings from Dement (1978) that counters the recuperation theory
- Randy Gardner kept awake for 260 hours
- after 14 hours sleep = back to normal
explain the effects of sleep deprivation in humans (with links to depression) (Vogel et al., 1975, 1990)
- found that depressed people go into REM sleep very easily but it is very disturbed
- preventing REM in depressed patients acts a an antidepressant
- if you suppress REM sleep, people want it more
- suppressing REM sleep and making body want it more regulates the irregular pattern of sleep that is seen in depressed people
describe the effects of sleep deprivation in animals
- after several days of sleep deprivation, animal died
- post-mortem showed swollen adrenal glands, gastric ulcers, internal bleeding
what brain areas are involved in sleep?
- hypothalamus
- reticular system
explain the role of the hypothalamus in sleep
- those who had difficulty sleeping had damage to anterior hypothalamus
- those who had difficulty staying awake had damage to posterior region of hypothalamus
