Dot Point 2 - Theories Of Sleep Flashcards
Evidence for the survival theory
Sleep depends on the need to find food; animals that need to graze for hours or find it difficult to find food, will sleep less.
E.g cows sleep for 3.9 hours a day
Sleep depends on an animals vulnerability to predators
E.g small very vulnerable animals will sleep more to hide and avoid predators (mice)
E.g larger prey animals will sleep less as they are exposed and can’t hide easily, (deer)
Sleep conserves energy ; an animals metabolism slows when sleeping
E.g, hibernating bears in the winter months
What is the Survival (evolutionary or adaptive) theory of sleep?
The survival theory proposes that sleep increases an organisms chances of survival within its environment.
Criticism of the survival theory
The theory assumes that sleep is useful but not essential. It doesn’t explain why we sleep
E.g sleep deprivation can kill
The theory assumes that sleep enables us to hide safely but due to lack of awareness we become more vulnerable to an attack
What is the Restorative theory of sleep
The restorative theory of sleep proposes that sleep helps us to replenish the body’s physical and mental resources
Evidence for the Restorative theory of sleep
People report feeling tired before sleeping and relates upon waking, it also enhances mood
Sleep increases alertness and consolidates memories (particularly REM sleep)
E.g when deprived of it, we are Inattentive, more easily distracted and poor memory
Sleep is a period of psychological rest; muscles are relaxed, bodily functions slow and neural activity is lowered
E.g ultra-marathon runners (92km) sleep deeper and longer for 2 days following their race
Damaged cells can be repaired; growth hormone is released at a higher rate
Criticism of restorative theory
There is little evidence to show that we sleep more than usual on particularly active days. 10 mins increase
Those who do little exercise or who are disabled do not sleep any led than those who are physically active
The brain is still active during sleep, particularly in REM and increased physical activity occurs during REM as well
