Theories Of Sleep
Sleep is used to restore the brain and body from demands placed upon it during the day.
happens through stage 3+4+REM sleep (core sleep)
Stages 1+2 are elastic sleep.
Sleep deprivation, growth, exercise put on extra strains so more sleep is needed after these activities.
Supporting + refuting evidence
Rechshaffen's Rat's- deprived of sleep = die. this is animals thought so.....
Peter Tripp - stayed awake for 200 hours. began to hallucinate without sleep it can't restore itself.
Green - High proportion of infants spend high proportion of sleep in REM. During 1st weeks alot of growing. more energy given = more sleep after, detailed case study + scientific weight
Randy Gardner - stayed awake for over 200 hours, no long lasting effects
Horne + Minard - exhausted participants. fell asleep quickly but didn't sleep longer. Don't need more sleep for more Strains WAS OBSERVATIONAL THOUGH!
Ecological Theory Of Sleep
Sleep can be adaptive for mammals
sleep has suvival benefits so it changes from species to species
some micro sleep + some sleep unbroken
has survival benefits as conserves valuable energy
Hibernation Theory (Webb)
It reduces energy demands at a time of year when they are hard to fulfill.
foraging animals = high metabolic rate = more energy used
Zepelin + Rechtshaffen - correlated body size + total sleep time in 53 species. negative correlation. High metabolic rate sleeps longer as suggested.
Only conserve 5-10% more energy
dolphins use 1 hemisphere at a time, must be another satisfied function as not conserving
sloths - low metabolic rate - 20hours sleep (outlier)
Time spent asleep relates to exposure to predators.
lions -> hunt-> infrequent-> not at risk-> lots of sleep
Deer-> grazing-> often-> at rick-> little sleep
so patterns of sleep do reflect relative survival benefits
Allison + ciahetti - correlated total sleepwith typical amount of danger. strong negative correlation more risk - less sleep, less risk - more sleep. patterns have evolved to reduce risk of predatation
if sleep is purely for protection, most risk shouldn't sleep.
rabbits+moles sleep the same but predatation risk varies.
being asleep may make you less conspicuous so should be the other way around
General Commentry On Ecological Theories
Explains the variation of sleep patterns
if these are true + sleep just "kills time" or keeps us safe, why did peter tripp react so badly to sleep deprivation.
Are humans and animals different?