Answer: Different things cause insomnia. It could be diet (caffeine, dinner too late, etc.), habit (biological alarm clock, computer use, etc.), environment (temperature, bed, clothes, etc.), mental (stress, not relaxed enough, depression, etc.) or some other health reason (see Internet for details). The best thing to do would be to keep a log of what you are thinking, feeling, eating, etc. for a few days, and then change something. Whatever you try, keep in mind that this is only an experiment to find out the cause of your insomnia, and if something doesn't work right away, don't worry, change doesn't happen overnight. If you've tried everything, and I mean EVERYTHING, talk to your doctor.