The majority of the adolescents needs around 8 ½ to more than 9 hours of dream every night. The correct amount of dream is essential for any person who wants to make or an examination or to practice a sport without tripping over her feet. Unfortunately, nevertheless, many adolescents do not sleep the sufficient thing. Why the adolescents not sleeping the sufficient thing? Until recently, the adolescents used to have bad fame to remain wide-awake until behind schedule, to sleep in excess for the school, and to remain slept in class. Nevertheless, recent studies show that the landlords of dream of the adolescents defer from those of the adults or children. These studies show that during the adolescence, the circadian rythm of the body (something as well as an internal biological clock) is temporarily regulates, making a person sleep later and they awake later. This change in the circadian rythm seems to be due to the fact that hormone cerebral melatonin takes place later at night for the adolescents than it is for adult children and. This can do more difficult for the adolescents to sleep early. These changes in the circadian rythm of the body agree with a little while in which more we are occupied than ever. For the majority of the adolescents, the pressure to do it in the school is more intense well than when they were young, and it is more difficult to leave ahead without studying hard. And the adolescents also have other demands of time - from the extracurricular sports and other activities to lean to a work part-time to save money for the university. The first times of beginning in some schools also can play a role in this deficit of dream. The adolescents who still fall asleep after the midnight can have to rise early for the school, which means that only every night can be tightened in 6 or 7 hours of dream. A pair of hours of lack of dream of one night can not seem a great thing, but it can create a deficit of dream in the time.