Several million Americans have chronic sleep problems and insomnia. Recent studies show that exercise may improve the quantity and quality of sleep.

Researchers are not sure why exercise may help sleep, but the physical mechanism may be a change in the balance between the parasympathetic and sympathetic nervous systems. Stimulating the sympathetic nervous system causes an increase in heart rate, blood pressure and metabolic rate which are counter productive to sleep. Stimulation of the parasympathetic nervous system causes the opposite effects.

During exercise, sympathetic activity increases, but later decreases relative to parasympathetic activity. This alteration between these two systems may allow individuals to fall asleep more quickly and sleep more deeply.

Morning exercise may be more effective at promoting sleep than evening exercise because of it's affects on the body's circadian (day and night) rhythms. Sleep experts, however, vary regarding timing of exercise.

Most kinds of exercise done at a moderate intensity may be effective in improving sleep. These include aerobic activity, interval training, and weightlifting. Stretching has also been shown to aid in better sleep patterns.

If you are one of the millions of Americans with sleep difficulties try a little exercise. It might be just what you need to get a better nights rest.