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Exercise and Sleep
The Exercise/Sleep Connection
Everyone's body temperature naturally goes up slightly in the daytime and back down at night, reaching its low just before dawn. Decreasing body temperature seems to be a trigger, signaling the body that it's time to sleep. Vigorous exercise temporarily raises the body temperature as much as two degrees.
Twenty or 30 minutes of aerobic exercise is sufficient
to keep the body temperature at this higher level for a period of four
to five hours, after which it drops lower than if you hadn't exercised.
This lower body temperature is what helps you sleep better. So if you
exercise five to six hours before going to bed, you will be attempting
to sleep at the same time your temperature is beginning to go down.
Exercise and sleep have a more complicated relationship than many people realize. The majority of people claim that they don't exercise on a regular basis because they are too tired. Hmmm. Could that have something to do with sleep habits, perhaps? Chances are good that it does.
If there were a competition to determine which lifestyle habit would win the title of "best intention never acted on," exercise would probably win. The reason we intend to exercise is that we all know how good it is for us. And research finds new benefits every day. Regular exercise improves heart health and blood pressure, builds bone and muscle, helps combat stress and muscle tension, and can even improve mood.
Add one more benefit: sound sleep. Did you know that exercise can help you sleep sounder and longer and feel more awake during the day? It's true. But the key is found in the type of exercise you choose and the time you participate in it during the day.
What time of the day do you think exercise would best help you sleep? Morning? Afternoon? Evening? Right before bed?
Exercising vigorously right before bed or within about three hours of your bedtime can actually make it harder to fall asleep. This surprises many people; it's often thought that a good workout before bed helps you feel more tired. In actuality, vigorous exercise right before bed stimulates your heart, brain and muscles -- the opposite of what you want at bedtime. It also raises your body temperature right before bed, which, you'll soon discover, is not what you want.
Morning exercise can relieve stress and improve mood. These effects can indirectly improve sleep, no doubt. To get a more direct sleep-promoting benefit from morning exercise, however, you can couple it with exposure to outdoor light. Being exposed to natural light in the morning, whether you're exercising or not, can improve your sleep at night by reinforcing your body's sleep-wake cycle.
When it comes to having a direct effect on getting a good night's sleep, it's vigorous exercise in the late afternoon or early evening that appears most beneficial. That's because it raises your body temperature above normal a few hours before bed, allowing it to start falling just as you're getting ready for bed. This decrease in body temperature appears to be a trigger that helps ease you into sleep.
The type of vigorous workout we're talking about is a cardiovascular workout. That means you engage in some activity in which you keep your heart rate up and your muscles pumping continuously for at least 20 minutes. Although strength-training, stretching, yoga, and other methods of exercise are beneficial, none match the sleep-enhancing benefits of cardiovascular exercise.
Try to schedule at least 20 minutes of vigorous exercise three or four times a week. Choose whatever activity you enjoy. Walk to and from work, or walk the dog. Jog, swim, bike, ski, jump rope, dance or play tennis -- just make it part of your routine.
If you have any serious medical conditions, are very overweight, or haven't exercised in years, talk to your doctor about your plans for exercising before you begin. Be sure to start exercising slowly, gradually increasing your workout time and intensity, so you don't get sidelined by injury. Remember, regular exercise can help you feel, look and sleep better.
The effect that sunlight has on the sleep-wake cycle can be just as complex. Learn about this connection on the next page.