Although the notion may seem counterintuitive, a quartet of exercises you can do in bed will help loosen tightly wound muscles and send you to sleep—no medication needed. "When you tense a muscle and hold it, there is muscle fatigue. So when you release the tension, the muscle wants to relax," says Martha Davis, Ph.D., psychologist and manager of the anxiety-disorders team at Kaiser Permanente's Santa Clara, California, facility and coauthor of The Relaxation and Stress Reduction Workbook. Isometric exercises—simply flexing and holding muscles for a short period of time—help leverage that relaxation impulse.

Davis suggests the following routine to remedy restlessness:

1. Lie on your back. Inhale through your nose, then exhale slowly. Continue doing this throughout the exercise.

2. Tense your toes tightly. Hold for a count of 10. Unclench. Now tense your entire foot. Pull your toes in. Hold it, then relax.

3. Tense your calves. Count to 10, then relax. Continue with thighs, buttocks, stomach, hands, arms, shoulders, neck, and face.

4. Finally, tighten as many muscles as possible in your body, hold as long as you can, and then let go. This exercise feels almost like a massage, Davis says. Repeat this step—if you aren't already asleep.