people should exercise more regularly. it is proven to help you sleep better and sounder. to fit more exercise in ur busy timetables, you can either a couple of things:
e.g. if u catch a bus, get off one stop eariler and walk to ur intended bus stop.
at lunchtimes or even at break, play some sport. a good old favourite is handball. the game can get very addictive. VERY.
after school, do some sport as well, even if it is playing some basketball, or jogging.
walk faster or jog to classes.
there are plenty others as well. also, eat well, drink lots of water and always try to be optomistic. stress and unhappiness are not good for you.
contrary to the time most people say its bedtime, for me it was 11pm, 11:30pm at the latest. get at least 7 hrs sleep, 8 hrs is optimal.
if ur really really really busy with assessments, it doesnt matter. ur sleep and health is more important. this means u need to manage your time better. cut down on ur play time a bit. perhaps do some maths homework or finish a chapter of ur perscribed text on the bus or on the train.
all these little things you do in between will add up in the end, and it pays off