Discuss evolutionary explanations of sleeo
Discuss evolutionary explanations of the functions of sleep.
Evolutionary explanation of sleep suggests there four mains reasons for it, energy conservation, foraging requirements, predator avoidance and to waste time. The evolutionary approach has also been called the ecological approach. It is called ‘ecological’ because it is based on observations of animals in their natural environment.
Energy conservation is the theory that warm blooded animals need to expend a lot of energy to maintain a constant body temperature, their high metabolic rates therefore cause them to need more sleep as a way of providing a period of enforced inactivity Webb 1982 described this as hibernation theory.
Zepelin and Rechtschaffen (1974) found that smaller animals, with higher metabolic rates, sleep more than larger animals. This supports the view that energy conservation might be the main reason for sleep. However there are many exceptions, such as sloths, which are very large yet sleep for 20 hours a day.
Another evolutionary explanation of the function of sleep is foraging requirements. The time spent sleeping may be constrained by food requirements, herbivores have constrained sleep as they have to eat grass constantly due to lack of nutrients such as cows, whereas carnivores however can afford to rest much of the time as they eat a variety of meats giving them these important nutrients.
Predator avoidance is another evolutionary explanation which suggests that if an animal is a predator then it can sleep for longer, whereas prey species cannot afford to sleep long as of predator risk. If sleep is a vital function then they are best to sleep when east vulnerable. Allison and Cicchetti (1976) found that species who had a higher risk of predation did sleep less, though again there were exceptions, such as rabbits who had a very high danger rating yet slept as much as moles who had a low danger rating.
Finally Meddis (1975) suggested the theory of ‘waste of time’ hypothesis.
Evolutionary explanation of sleep suggests there four mains reasons for it, energy conservation, foraging requirements, predator avoidance and to waste time. The evolutionary approach has also been called the ecological approach. It is called ‘ecological’ because it is based on observations of animals in their natural environment.
Energy conservation is the theory that warm blooded animals need to expend a lot of energy to maintain a constant body temperature, their high metabolic rates therefore cause them to need more sleep as a way of providing a period of enforced inactivity Webb 1982 described this as hibernation theory.
Zepelin and Rechtschaffen (1974) found that smaller animals, with higher metabolic rates, sleep more than larger animals. This supports the view that energy conservation might be the main reason for sleep. However there are many exceptions, such as sloths, which are very large yet sleep for 20 hours a day.
Another evolutionary explanation of the function of sleep is foraging requirements. The time spent sleeping may be constrained by food requirements, herbivores have constrained sleep as they have to eat grass constantly due to lack of nutrients such as cows, whereas carnivores however can afford to rest much of the time as they eat a variety of meats giving them these important nutrients.
Predator avoidance is another evolutionary explanation which suggests that if an animal is a predator then it can sleep for longer, whereas prey species cannot afford to sleep long as of predator risk. If sleep is a vital function then they are best to sleep when east vulnerable. Allison and Cicchetti (1976) found that species who had a higher risk of predation did sleep less, though again there were exceptions, such as rabbits who had a very high danger rating yet slept as much as moles who had a low danger rating.
Finally Meddis (1975) suggested the theory of ‘waste of time’ hypothesis.