Sleep

Sleep is a natural state of rest for the body and mind, characterized by a reduction in consciousness and muscle activity, relatively inhibited sensory activity, inhibition of nearly all voluntary muscles, and reduced interactions with surroundings. Sleep is an essential part of maintaining good health and well-being and plays a key role in physical, mental, and emotional processes, such as memory consolidation, hormone regulation, and immune function. Mammals sleep occurs in repeating periods, in which the body alternates between two highly distinct modes known as non-REM ( Rapid Eye Movement) and REM sleep. Most adults need 7-8 hours of sleep per night to function optimally.