Functions of Sleep
There are two approaches;
The Restoration Explanation
This suggests that after using all our energy in the day, we have to sleep to restore fatigue and restore our physiological systems in the body
Sleep has a homerostatic function which is the maintenace of a constant internal environment so sleep contributes to this by restoring the physiological systems to their optimim level.
Oswald (1980): He observed patients that were recovering from brain damage and they spent more time in REM sleep. He noted the deep stages of NREM as there was a surge of hormone release. Growth hormone is essential in the maintenance of the body's repair of its physiological systems
Horne (1988): Based on a large number of lab-based sleep deprivation studies. The studies assume that assessing the effects of not sleeping willl help understand the normal function of sleep. He reviewed 50 studies
* Mild sleep deprivation had little/no effect - some severe cases did not have dramatic consequences
* There were concentrated on cognitive functions such as attention, perception and memory
* When they were allowed to sleep, they recovered more REM than NREM --> lost to lighter sleep
Horne suggested that REM and NREM ('core sleep') essential for maintaing brain systems that underlie cognitive processes. Light NREM = no key function 'optional sleep'
Sleep not related to bodily restoration which took place during 'relaxed wakefulness'
Animal deprivation studies - Severe deprivation was done on rats that lead to death supporting the resporation explanation. However keeping rats awake involves contant arousal and stress
--> fatal. No single cause in the rats have been found.
Fatal Familial Insomnia - inherited condition affecting sleep in the middle aged where they stop sleeping. Death occurs within 2 years. FFI = damage to the thalamus. Death caused by damage to the thalamus not sleep deprivation?
Energy Conservation - Expending physical energy --> extended sleep (If Oswald correct) Not consistent. Evidence that people who exercise causes people to fall asleep faster but not sleep longer (Breedlove et al 2007) CONDICTS OSWALD