ABSTRACT
Oswald suggested that both REM and NREM sleep serve the purpose of restoring and replenishing our bodies and brains. He suggests that NREM sleep is needed more for restoring bodily processes which have deteriorated or been worn down by the day and REM sleep is the main time for renewing brain processes and replenishing neurochemicals used up in the day that need to be regenerated by protein synthesis. The sleep patterns of some animals raise further questions for restoration theory. The evolutionary or ecological theory, suggested by Meddis, proposes that sleep could be a time of increased safety as animals are immobile and therefore less likely to be noticed by predators. So their sleep patterns still fit in with an evolutionary theory. The neurochemical approach or theory suggests that sleep has a particular function(s) within the brain, a specialised sort of restoration theory.
