The evolutionary theory of sleep suggests that there was osme
evolutioary advantage to sleeping, other than to restore us.
Predator-prey sleep; Meddis (1979) believes that sleep evolved to
keep animals hidden from predators when usual activities, like forgaing
are not required. Those who survive are able to pass on genes.
Hibernation theory; Webb (1982) beleives that active animals need
larger amounts of food, threatneing survival during times of food
scarcity. Hibernation conserves energy thus increasing survival.
In support of this; Stear (2005) reported that
sleep saves energy, keeps individuals from being
lively at unnecessary times and is an adaptation
to ecological factors differing across species,
supporting the evolutionary basis of sleep
Foraging needs; animals which eat food containing few calories, like
grass, need to eat more an dfor longer and so would have to sleep
less to survive and pass on genes. Animals eating calorie rich foods
could afford to sleep more as they would not need to eat all the time
Aquatic mammals; the precise enviromental demands of
species affect sleep patterns and behaviours. Aquatic
mammals need to breathe, so sleep incurs a rise of drowning.
Body size; smaller
animals evolved a
greater need to
sleep, their
metabolic rates
being high and
energy
consumption rapid.
Long periods of
sleep helps to
consever energy
stores.
Requadt (2006) found that animals locate warm, safe places to sleep
as it minimises energy requirements to maintain body temperature,
supporting the evolutionary point of veiw
Alison and Cicchetti (1976) studied sleep patterns in 39 animal species. They found that
prey species were likely to spend only short amounts of time asleep which disagress with
Meddis' theory of predator avoidance. However, prey animals are usually herbivores and
would require to be awake for longer in order to find enough food.
Siegal (2008) reported that there is a less risk of
injury when asleep than awake, sleep being a safety
device when essential activities are not requires.
A lot of research involving evolutionary explainations depends on animals
studies, incuring a problem with generalising animals to humans