I can't sleep at night...and don't know why.?

omg i had this same problem last year!! i wouldnt be able to go to sleep until like 12 and i would wake up at like 5 and not be able to go back to sleep! it may be stress or in my case i just kept thinking i cant sleep i cant sleep i cant sleep and i wouldnt sleep! but during the summer when i wasnt stressed about school or anything or about going to sleep at a specific time i slept like a baby! i still have problems sometimes, but it not as bad. to help me sleep and calm down i make a schedule for my brain to know when to relax. first i watch tv for a period of time and then take a shower and make myself some tea WITHOUT caffeine. make sure the tea has chamomile because it helps the body calm down. then i go to bed and read for a couple min and im ready to sleep!so i suggest u make a routine for yourself to trick ur brain to making it think its time for sleep. u could also try Melatonin which is a natural herb or something :)