Sleep and eating are the essential mechanisms which help us to maintain normal conditions for life. If sufficient food provides us with the energy and material for building tissues, sleep is the way no normalize hormonal imbalance which emerges during the day. Hours of rest help us to recharge our batteries and allow to perform mundane tasks easily and quickly. Regular deficiency of night sleep, consequently, disturbs our well-being and makes even the simplest everyday tasks unmanageable.
Researchers developed several theories to explain why actually humans need this mechanism of sleeping. The earliest theory of sleep suggests that human inactivity in the night time is dictated be the natural instinct to survive. In the wild nature, animals which remained still at night had more chances to avoid being killed by predators. According to another theory, night sleep helped humans to conserve energy acquired during the daytime. Most modern societies are plentiful of food, but our forefathers frequently had difficulties with finding something to eat and feeding their families. Restorative theory of sleep suggests that sleep is an opportunity to restore energy spent during the day as major restorative functions of the body are performed during sleep. Our muscles grow, tissues repair, and hormones come at balance always when we sleep.
At the present moment these theories are unproven, however, we may find common sense in each of them. Night sleep is a potent regulator of our bodily functions, as countless processes are triggered in cells and tissues while we are inactive. Moreover, there are specific processes such as repairing of the liver tissues which can occur only during the night sleep.