Unveiling sleep mysteries: functions

Résumé

Sleep occupies roughly one-third of human lives, yet it is still not entirely  scientifically clear about its purpose or function. However, the latest research achievement concluded that sleeping has much more effect on the brain than formerly believed. Much of these studies are about the effects of sleep  deprivation, and the glymphatic pathway initially identified in the rodent brain. In this paper, it is presented some of the theories about sleep functions, besides a review of some physiologic function of sleep. Now, it is accepted that sleep is involved with cleaning the brain toxins, physical restoration, information processing and recall, regulation, besides strengthening the immune system. Sleep implies in a neuronal activity markedly different along with its phases. It is regulated by two parallel mechanisms, homeostatic and circadian. Besides, the sleep-waking cycle involves diverse brain circuits and neurotransmitters and their interaction is explained using a flip-flop model. Several theories may help clarify the reasons human beings spend an important part of their lives sleeping such as those of Inactivity, Energy Conservation, Restorative, and Brain Plasticity. Recently, it was emphasized the importance of the glymphatic system that is a waste clearence system that acts mainly during sleep support efficient removal of soluble proteins and metabolites from the central nervous system. Indeed, sleep meet the needs of higher brain functions along with basic vital processes.