Q: You recently recommended exercise as a way to improve sleep. But if it’s done in the evening, won’t it have a negative effect on sleep?
A: Not necessarily. Standard sleep advice says you shouldn’t exercise moderately or vigorously within a few hours of bedtime. It’s true that for most people it’s not a good idea to exercise right before bedtime. But surprisingly, most studies have found that early evening exercise does not impair sleep quality.
A Brazilian study published in Sleep Medicine in 2011, for instance, found that treadmill workouts starting at 6:00 p.m. were just as effective in improving sleep in middle-aged people with chronic insomnia as sessions done in the morning.
Another Brazilian study, in Psychophysiology this year, found that moderate aerobic exercise done at 8:00 p.m. helped promote sleep in young men who went to bed two to three hours later. Similarly, a 2004 study of older people, published in the journal Sleep, found that activity (including low-impact aerobics) done between 7:00 p.m. and 8:30 p.m. improved sleep as well as morning workouts did.
Exercise has a variety of potentially sleep-impairing and sleep-enhancing effects on the body. Notably, it can raise heart rate, body temperature and alertness, which, if they remain elevated, could interfere with sleep. On the other hand, exercise can help reduce anxiety, a plus for sleep.
Keep in mind, the effects of exercise on sleep can vary from person to person, and will depend not only on fitness level and sleep problems, if any, but also the type, length, timing and intensity of the workout. If you think evening exercise is interfering with your sleep, see if earlier workouts improve matters.