> OSWALD proposed that SWS & REM had different functions - SWS enables body repair & REM enables brain recovery.
Slow wave sleep (SWS)
> Growth hormone is secreted during SWS (stimulates growth & is thus important during childhood - also important in adulthood as it enables protein synthesis & cell growth to take place.
> Protein synthesis & cell growth is vital in the restoration of body tissue as proteins are fragile & must be constantly renewed - this constant restoration of vital proteins is part of the body's natural recovery process.
> Growth hormone is secreted in pulses through the day but a significant amount is released at night and mainly during SWS.
> SASSIN ET AL. found that, when sleep-waking cycles are reversed by 12 hours (person goes to sleep in morning and gets up at night), the release of GH with sleep is also reversed. Shows that GH release is controlled by neural mechanisms related to SWS.
> Research found that the amount of growth hormone released correlates with the amount of --- & the decline of growth hormone in older age has also been associated with reduced SWS.
The immune system -
> KRUEGER ET AL. found that lack of SWS is associated with reduced functioning of the immune system - the body's system of defence against viruses and bacteria.
> The immune system consists of various protein molecules - antibodies - which are regenerated during cell growth and protein synthesis in SWS.
Brain growth -
> SIEGEL suggested the amount of REM sleep in any species is proportional to the immaturity of the offspring at birth. (the platypus is immature at birth & has 8 hours of REM sleep a day, whereas the dolphin can swim from birth & has almost no REM sleep).
Neurotransmitter activity -
> SIEGEL AND ROGAWSKI suggest that REM sleep allows for a break in neurotransmitter release which in turn permits neurons to regain their sensitivity and allow the body to function properly.
> Antidepressant drugs, such as MAOI's, aim to increase the levels of neurotransmitters of the monoamine group (like dopamine & serotonin) - a side effect of MAOI's is that they abolish REM activity completely.
> One suggestion for why MAOI's abolish REM activity is that the two are linked - the increase in monoamines means that monoamine receptors don't have to be revitalised & therefore there's no need for REM sleep.
REM sleep and memory -
> CRICK AND MITCHISON proposed that during REM sleep, unwanted memories are discarded, thus making more important memories accessible.
> Evidence currently suggests that REM may be important in the consolidation of procedural memory (skills like riding…