Are you using electronics (computer, iPad, phone) just before bed? There's a lot of research that shows this is really not good for our brains to quiet down and be ready for sleep. Stop using all your electronics an hour before bed; instead, read or listen to calming music.
When you are lying still for a long time your body sends roll over signals to the mind, to test if the mind is asleep. If you respond to a roll over signal (ex. Scratching your nose, rolling over, just moving in general) your body will wake up. Resist the urge to move and relax your mind