A normal person spends about 8 hours daily, or one-third of the lifetime in sleeping. Nobody knows exactly why we sleep, but it is essential for both the mind and the body. The duration of sleep depends on a person’s age, health and the type of work he or she does during the day. Rest is required to make the body and mind fresh and keep them healthy. A newborn baby sleeps nearly all day. The child wakes up only at feeding time. A young child sleeps for about 12 hours a day. An adult generally needs a sleep for about 8 hours a day. After sleep, one feels refreshed and energetic. Someone who does not take rest for 36 hours at a stretch, becomes irritable and tired. If he manages to stay awake without collapsing for over 60 hours, he may begin to ‘see’ and ‘hear’ things that are not there. Hence, rest is a must for every one to keep the body and mind active and alert.