Every night, almost every human being is subject to an unusual change: we leave our awake consciousness and enter into a situation that is expressed as sleep for a few hours. With Waking, we remember little or nothing about those hours. Apart from some rare examples, we cannot think or think that we are asleep. Although the element of sleep applies to every person, many people are forced to undergo a full sleep state. All organisms display a model of alertness and a daily sleep-like activity and rest pattern in humans.