You could be stressed. I know I had sleeping problems for a while, and they had no idea why, and neither did I. Try taking melatonin. you can find it with the vitamins, and its basically a natural hormone in your body that re-sets the 24-hour sleep-wake cycle. Start with a small dose, and if that doesn't work, try a higher dose.
well it means you cant sleep have things in your head unable to stop thinking when your trying to stop thinking and you mind keeps on persisting and staying up all night having very few hours of sleep also called insomnia