Sleep deprevation is not a very healthy thing for your body at all. A minimum of seven hours sleep is required per 24 hours. This gives the body and the brain time to repair and replace needed cells. It relaxes the body to to take away all the tension of the day. As you deprive yourself of this needed sleep, you stand a chance of serious tissue, brain and bodily function damage. We lose our alertness the longer we stay awake. The body tires and in some cases, takes days to recover. Syptoms of lack of sleep are, irritability, stress, not focussing, blurred eye sight, inabilitty to stand for lengthis of time, forgetfulness, and losing track of time. There are others, but these are the major signs. Source is general taught knowledge in your text books in High School.