Sleep Flashcards
In what ways can sleep be measured?
Electro…
- encephalogram (EEG)
- oculargram (EOG)
- myogram (EMG, neck).
Why is it difficult to measure sleep on the first night of a study?
The first-night phenomenon.
What are pre-sleep alpha waves?
Bursts of 8 - 12Hz activity in low amplitude high frequency waves
What are sleep spindles?
1-2 second bursts of 12-14Hz waves in stage 2
What is a K complex?
Single large upward then downwards deflection (like a stage 4 wave) in stage 2.
Sleep is progressive and ____ in amplitude through the 4 stages of N-REM.
increases
Sleep is progressive and ____ in frequency through the 4 stages of N-REM.
decreases
How long are sleep cycles?
90 minutes.
What do we do whilst asleep that we don’t recall, and why don’t we remember it?
Short bursts of wakefulness, don’t remember due to memory consolidation effect.
Is there a dream-real time difference?
No, dream time correlates with real time.
After the first cycle of sleep, what happens physiologically?
- Lack of core movement/muscle tone.
- Periods of REM sleep associated with dreaming.
Why is REM sleep associated with dreaming?
Because you’re 80% more likely to remember dreams if woken during REM.
What are the two main types of theories of the function of sleep?
Recuperation and evolutionary.
What is the main premise of recuperation theories of sleep?
Being awake disrupts homeostasis, which is restored by sleep, e.g. it restores energy levels.
What are the main ideas behind evolutionary theories of sleep?
Sleep evolved in humans to prevent accidents and predation at night - it’s an unnecessary evolutionary atavism related to vulnerability and time spent eating.
e.g. predators have a low risk of predation and can easily satisfy feeding needs, therefore they characteristically sleep for long periods - Lions will sleep for 2 days after a kill.
What are the main criticisms of recuperation theories?
- Animal sleep (fish, species difference, sloths)
- Exercise has little effect on sleep duration in humans (Youngstedt and Kline, 2006).
- We don’t regain missed sleep.
What are the main criticisms of evolutionary theories of sleep?
- Sleep deprivation is fatal in animals (rats on moving platform, postmortem showed swollen adrenal glands, gastric ulcers and internal bleeding - Rechtschaffen 1993)
- Predation risk and eating habits can at most explain 60% of species variation.
- Sleep is universal therefore must have some function.
What are the main points concerning animal sleep?
- Fish, reptiles and amphibians don’t sleep, they just have periods of inactivity.
- The large species difference in sleep suggest it’s not related to size or temperature.
- Sloths hardly move but need to sleep 20hrs/day.
What predictions do recuperation theories make about the effects of sleep deprivation?
- It causes physiological/behavioural disturbances.
- After deprivation, missed sleep must be regained.
What did Cirelli (2006) find?
Sleep deprivation influences mood, physiological function and molecular function. Supports recuperation theories.
What did Curcio et al (2006) find?
That sleep deprivation has various effects on executive function: assimilating changing information, updating plans and reference memory.
What does Dement (1978) point out?
That people recover well after sleep deprivation, e.g. Randy Gardener was awake for 260hrs and recovered after 14hrs sleep.
What did Webb and Agnew (1967) find?
That preventing REM makes the body want it more - it’s the body’s default as it’s easier to maintain.
What did Brunner et al (1990) state?
That deprivation of REM causes a transient rebound.
Are there any cognitive or emotional effects of REM deprivation?
No.
What are the main brain areas involved in sleep?
- The hypothalamus
- The reticular system
What has research shown about the role of the hypothalamus in sleep?
- Von Economo studied brains of people who’d died from encephalitis lethargica - difficulty sleeping = anterior region damage, difficulty staying awake = posterior region damage.
- Saper et al (2001) confirmed with lesion studies in animals.
What has research shown about the role of the reticular system in sleep?
- Bremer (1936) found that a cerveau isole transection = only SWS, and an encephale isole transection = normal cycle, therefore wakefulness area between the two.
- Mouzzi and Morgan (1949) found that stimulation of sleeping cats’ reticular formation woke them up.
What is narcolepsy?
Periods of sudden sleep with loss of muscle tone.
What is the problem with REM sleep without core muscle atonia?
It can cause sleepwalking or a lot of movement whilst dreaming, which can be dangerous.
