There are different reasons you can't sleep, for example:
1. You're awake for no reason, with your mind spinning.
Middle-of-the-night worrying is probably the number-one type of sleeplessness faced by people of all ages. And boy, is it frustrating. You know you need to relax and get back to sleep, but anxious thoughts and to-do list items keep popping into your head.
2. You wake up to use the bathroom and can't get back to sleep.
Whether it's once a night or over and over, popping awake to use the bathroom disrupts your sleep cycle and cuts into your restful REM sleep. The best solution for this problem, officially called "nocturia," is prevention. If you don't wake up in the first place, you won't lose those precious zzz's.
3. Pain wakes you up.
Chronic pain of all kinds is one of the most common sleep disrupters; between 60 and 90 percent of people who suffer from some type of chronic pain sleep poorly. Mild pain can have as profound an effect on sleep as extreme pain -- yet many people don't take pain's effect on sleep seriously.
4. Your environment won't let you sleep.
Light, sound, temperature changes, and vibrations all have the effect of putting your body on alert. When subjects don't fully awaken from exposure to stimuli, they experience "microarousals" that disrupt sleep.
5. Your digestive system won't let you sleep.
A growling stomach can wake you and heartburn or gas can leave you lying awake in misery. Then there's gastroesophageal reflux disease, which can disrupt your sleep without you realizing it. (You might wake with a sour taste in your mouth but not know what woke you.)
Here's what you can do :
(1,2,4). Preserve the darkness. Keep the room dark when you wake up. Whatever you do, don't turn on the overhead light at night, use a little night-light to guide your way through your room/bathroom.
(1,4). Move the clock out of reach. Constantly checking the clock and calculating how long you've been awake only feeds your anxiety: "Oh no, now I'm only going to get five hours of sleep." Set the alarm, then move the clock where you can't see or check it.
(3,5). Breathe and ease. First, do "belly breathing," which means breathing deeply enough that your diaphragm rises and falls. Next, isolate each part of your body, from your feet up to your neck, by tensing and relaxing it. Finally, imagine yourself in a favorite place, such as lying in the sun on the beach. Use all of your senses; imagine that you're hearing the waves and smelling the salt air. If it doesn't work the first time, do all three steps again in the same order.