A. recent research shows that lots of teenagers are suffering from lack of sleep which is causing problems with their behaviour and learning. as a result schools have introduced a new lesson where students are given more of an idea of the importance of sleep. according to medical data, they should get at least nine hours' sleep a night. young people should realise that sleep is very important if they want to do well at school and enjoy life. b. it’s common knowledge that people sleep best in a dark room that is slightly cool. it's important to close your blinds or curtains and make sure they're heavy enough to block out the light. you can add extra blankets or wear pyjamas if you're cold. note that an uncomfortable bed, heat and noise can ruin a good night's sleep. a tv is also a distraction. c. if you don’t sleep enough or have a disturbed sleep you can get heart disease, high blood pressure and even diabetes. people who don't sleep enough get colds and flu more often than those who do. moreover, recent research proves that poor sleepers gain weight more easily than people who sleep well. extra kilos are the reaction of the body to the stressful sleepless situation. d. think twice before watching a movie late at night. don’t spend sleeping time on endless computer games. the thing is that by getting up and going to bed at the same time every day, even on weekends, you teach your body to follow a healthy regime. you'll quickly fall asleep, will have a good night’s sleep and will wake up at the expected time feeling fresh and active. e. some easy steps can prepare your body for going to sleep. you probably have some regular bedtime habits, even if you don’t realise it. brushing your teeth, taking a shower, reading a book and setting your alarm clock may all be part of your evening routine. remember that you should perform these activities in the same manner and in the same order every night. f. sleepless nights at exam time are very bad for students. if you prepare for your exam late at night, it will not improve your performance during the exam. on the contrary, it will affect your ability to concentrate, to react quickly and to analyse information. recent research shows that the results of the tests written after sleepless nights are lower than usual grades. g. if you think that during sleep, the brain rests, you're mistaken. it's a common myth about sleep. sleep is definitely needed – but it's not your brain that needs to rest, it's your body that needs to relax. your brain is still working when you're asleep, controlling physical functions like breathing and your heart beat. however, because the brain does not have to go through the constant stress of thinking, you get up refreshed and recharged.