During the deepest stages of the sleep cycle, the immune system repairs damage inflicted on the body. (naturesharmony.com)
It has long been thought that the amount of time spent in different stages of sleep was responsible for how well people were able to remember things. (entrepreneur.com)
The studies done on the subject of sleep and memory identify the last 3 stages of the sleep cycle as the most essential periods of memory consolidation. (progressivehealth.com)