If it's some kind of reaction of stress, then I can give you the tip to relax your body - one part at a time - when lying in bed, ready to sleep.
Like, just empty your mind, and count to 5 and then you relax your feet. Then your legs. Then your arms, your neck, your chest, your stomach, and lastly your head. (with a slight pause between each relaxing-part).

It've worked for me several times :)