Match the halves of the sentences :1Melatonin is a hormone .2People wake up in the morning .3Your body clock.4 Teenagers are tired in the morning 5 It isn't a problem for children 6 Bright light and loud noise 7 It's worse for American students 8Some scientists think that a) stop you falling asleep b) because they start school earlier c) comtrols the production of melatonin d) because they wake ip naturally at 7am e) teenagers shouldn't go to school till 10 am . f) because their body stops producing melatonin g) because they don't get enoigh sleep. h) that makes you feel sleepy. VA ROGGG E URGENT