try a meditation
exercise when you lay down in bed. try to focus only on your breathing and count 10 inhale/exhale cycles without thinking about anything else. If your thoughts wander to other things, start over again at one. This may relax your body and lower your heart rate
Another technique is to try to relax your body gradually, starting at your toes. focus on letting all muscle control flow out of your toes, so they are completely relaxed. Then move to your feet, then calves, then thighs etc. You should fall asleep before you get to your head.