The Exercise-Sleep Connection

Studies show that exercise can have both a positive and negative effect on one's sleep, depending upon who exercises and how soon you exercise to the time you go to sleep.

The down side: people who are not physically fit and exercise within 6 hours of going to bed are likely to fragment their sleep, possibly because of aches and pains. Because of this, experts recommend exercising early in the day for patients who aren't physically fit.

For patients who are physically fit, the timing of the exercise generally doesn't make any difference. Interestingly, for physically fit patients, not exercising at all can lead to insomnia - but researchers aren't yet sure why.

The up side: those with severe sleep apnea, or depression who go out and exercise tend to feel better and accomplish more in the daytime. Walking and weight lifting help - especially for the elderly.