Although we are exposed to potential attackers in sleep, sleep is one of evolution’s winners.
But what’s happening during sleep?
Why does our brain need to sleep?
Recent studies (e.g. Ji and Wilson, 2007) support the hypothesis of a replay of experiences during sleep. By repeating experiences of the day memory contents can be (re-)structured and solidified.
But not only our memory seems to benefit from excursions into the realm of dreams. In particular, the results of some sleep deprivation experiments (e.g. Lo et al., 2012), point to the importance of a healthy sleep on cognitive performance (continuous attention, working memory, etc.).
Furthermore: In particular in light of the circadian rhythm arises the question: When should a business day (or school day) begin?