Functions Of Sleep (Energy Conservation) Flashcards
Evolutionary explanation
- Sleep serves some adaptive purpose.
- Sleep of some sort evolved in all species which suggests it’s essential to survival.
- Each AS faces own set of evo pressure exp many observed cross-species variations in sleep.
- Reflecting different adaptive responses to these pressures.
- TF Sleep doesn’t serve same purpose in all species but its core function is to adapt AS to its specific environment.
Webb: Energy conservation (Hibernation explanation)
-Sleep; conserve energy by inactive when inefficient to be awake. -EC whilst awake = BT, foraging food and escaping predators . -Warm Blooded Animals spend ^energy maintain a constant BT. -Problematic for v animals with ^MR, -Animals adapted to DTA waste valuable E being awake at night when they would be unable to hunt/forage. -Empson; “animals simply bide time until their env = favourable” -So the FOS is to ‘waste time’. Sleep = period of enforced inactivity much like hibernation.
Zeppelin et al: support (metabolic rate)
-Found that MR and animal size did relate to time spent sleeping.
–ve correlation in smaller animals (^MR) who slept longer sleeping than larger animals which supports the idea that sleeps main function is energy conservation. -// this r is not true all species; some larger species (v MR) sleep for longer periods of time. -Giant sloth sleep for 20 hrs a day in captivity. -Evolution cannot fully explain all sleep phenomena.
Captive animals
highlights an issue with animal research. -SB in captivity not tsame as sleeping in wild. -Recent reports = giant sloth sleeps 6 hrs^ in zoos than in wild. -Wild sleep v captive ones; ^ concerned with predation/feeding. -AT ethically + metho ^ difficult, R with wild animals is more likely to reveal the true functions of sleep.
Rest as adaptive as sleep
-Contradiction = rest appears as adaptive as sleep does. -Energy conservation in sleep is minimal, vMR 5-10% cprd to rest. -Risks associated with sleeping (vulnerability to predation) would outweigh advantage of energy conservation. -ECE appears incomplete; not holistic exp for functions of sleep.
Little brown bat: reductionist, v EV
-Little brown bat exemplifies CoE theory; only wakes for a few hours a day to feed before going back to sleep. -Support theory sleep aids in survival and energy conservation. -// if this is the case and animals wake just to feed/reproduce; argued such beh = universal in all animals seems most adaptive. -Reductionist; simply adaptive response//far more complex/unique across species. -Bat study v EV GWC to other animals or humans due to different env pressures resulting in different adaptive behaviors.
Meddis: predator avoidance theory
- Sleep time is correlated with danger.
- prey species sleep v to remain vigilant and avoid predators. -prey animals developed SP which enhance survival. -Meddis; sleep enables PA adapted to daytime activity bc unsafe during night when poor night vision ^risk of attack. -Grazing animals sleep v as out in open; vulnerable to predation. -Predators sleep for longer than their prey but this depends upon place in food chain as many predators are also prey for larger animals.
Allison and Ciccheti: support (39 animals)
-Analysed sleep patterns in 39 animal species. found -ve correlation between predation risk and sleep amount. -TF Animals with ^ env danger spent less time sleeping. -//These findings didnt apply to all animal species e.g. rabbits slept as much as moles even though rabbits have a much higher danger rating than moles.
Unfalsifiability of evolutionary explanation
-disadvantage= explain completely opposite phenomena. -sleeping ^ or for v periods seen as adaptive in any prey species. -^ periods would conserve energy and v visibility to predators, = dealing with and/or avoiding predators. -v periods aids alertness to better avoid predators. -Unique nature of different species; single Evo exp insufficient as theory is unfalsifiable.
