Sleep Flashcards
Functions of sleep
Restoration
Evolution
Maintaining brain plasticity
Basics of sleep
There are four stages of slow wave sleep
After slow wave sleep the body progresses into REM sleep.
Measured using an EEG
Lifespan changes in length of REM sleep.
50% at birth
20% in old age
Insomnia
Primary-lack of sleep main problem
Secondary- lack of sleep due to another problem.
Sleep apnoea - related to a form of secondary insomnia
Apnoea- difficulties breathing when asleep
CSA apnoea -Brain forgets to send breathing messages
OSA apnoea- Narrowing of airways- upper airway relaxes
Brief inability to breathe- occurs when 1+ breath’s are missed
Continuous positive air pressure
Sleep walking
Somnambulism
REM behaviour disorder
Narcolepsy
Extreme sleepiness during the day
Cataplexy- muscles give way
What three methods are used in distinguishing between the different stages of sleep?
EOG- Electrooculogram- measures eye movement
EEG- Electroencephalograph-measures brain waves
EMG- Electromyogram- measures muscle movement
What happens in stage 1 of non rem sleep?
Person becomes relaxed, heart rate slows, eyes may roll and muscles relax. EEG shows theta waves.
What happens in stage 2 of non rem sleep?
EEG pattern of sleep spindles- short bursts of high frequency activity.
What happens in stage 3 of non rem sleep?
EEG shows dominant delta waves (large amplitude slow waves) sleep spindles occur less often.
Heart rate and body temperature drops.
What happens in stage 4 of non rem sleep?
EEG shows mainly delta activity, deep sleep, hard to wake.
What is the Restoration theory?
That sleep restores the body to full psychological and physical capacity
Oswald 1980- patients recovering show an increase in REM sleep. An increase in rem means an increase in protein synthesis.
Horne 1988- sleep deprivation-sleep recovery mainly happens in stage 4 and rem.
Rem sleep deprivation case study-Empson 2002-
Researchers woke sleepers as soon as they entered rem sleep- if awoken and allowed to sleep again they normally go back into rem sleep - when then allowed to experience rem sleep they experienced 50% more rem sleep than normal.
Evolutionary approach to the function of sleep
What are adaptive behaviours?
Behaviours that increase an animals chance of survival and reproduction.
Sleep= conservation of energy-most likely to survive
Evolutionary approach to the function of sleep
What evidence is there for the evolutionary approach?
Small animals- high metabolic rates- lose heat fast- sleep longer than large animals
Zepelin&rechtschaffen 1974- 53 species- pos correlation between daily sleep length and species’ metabolic rate
Limitation- some large slow animals sleep a lot- sloth.
Evolutionary approach to the function of sleep
Foraging- animals would sleep more if they had a nutrient rich diet
Extract more from food in less time and then sleep longer= conservation of more energy.
Evidence-panda just eats bamboo=poor quant of nutrients- eat 16 hours out of 24= eat 45kg= eat 8hrs-sleep 4.
Evolutionary approach to the function of sleep
What should happen when food is scarce?
Evolutionary approaches would suggest that sleep time should increase- greater need to conserve energy
Evidence- Berger & Phillips 1995- animals do either increase sleep time or reduce body temperature.
Evolutionary approach to the function of sleep
How do animals avoid predators?
Sleep in safe places in the hours of darkness when they are most vulnerable
Evidence- Allison & cicchetti 1976-
Correlational analysis- less sleep in day if they’re in a dangerous environment- 39 species - neg correlation between sleep and level of environmental danger
Describe the 3 p model for insomnia…
Predisposition- a factor that increases likelihood of insomnia
Precipitation- a factor that triggers insomnia
Perpetuation- factors that have a maintaining effect on insomnia.
What evidence is there for the 3p model and predisposition?
Spiel man 1987- affected by anxiety, depression, and emotions- study found insomniacs have an increased heart rate (in response to stress) and metabolic rate- increased physiological arousal assiciated with insomnia.
Some studies suggest worrying about insomnia is a factors other studies have found correlations opposing a personality alignment.
What happens in rem sleep?
High frequency, small amplitude beta waves
EOG= rapid eye movement
EMG= muscles completely relaxed
EEG= similar to person awake= heart rate and respiration speed up
-body acts as if paralysed= paradoxical sleep
Dreams occur most often in….
REM SLEEP
What order do the stages of sleep happen in?
1-2-3-4-3-2
Children have the most rem sleep when….
They are a foetus,
Horne suggests that rem sleep helps…
Stimulate the brain in the foetus, when they are in the ‘real’ world it is replaced by outside world stimulation.
Up to the age of 45 what percentage of sleep is REM?
15-25%
