Physical activity can affect the body’s temperature and metabolic rate, which in turn affects sleep. Physical exercise causes various changes in metabolism and hormones, which stimulate and raise the body temperature. Sleep is relatively easy when body temperature drops, and if we want to improve sleep through exercise, it is best not to exhaust ourselves in the evening. Early studies found that heavy daytime labor can promote sleep that night, but that labor must end five or six hours before bedtime. The relaxation that comes with exercise helps us get enough deep sleep. So, how much exercise is needed to improve sleep? Probably less than you’d think – 20 minutes three times a week. Of course you want to do aerobic exercise, which increases oxygen consumption, improves breathing, and strengthens the heart and blood circulation – whatever is good for your health must also be good for your sleep. The most important point is that any exercise can improve sleep when the exercise center jump frequency reaches the “target range”. (Target range calculation: 220 minus your age to get the maximum heart rate for your age. Then calculate 60% and 75% of this number, which is the lower and upper limits of your heart rate during exercise.) For example, if you are 35 years old, 220-35=185, this number is your maximum heart rate; 60% and 75% of this number are 111 and 138 respectively, so your ideal heart rate in exercise should be between 111 and 138. Any aerobic exercise, such as cycling, swimming, jogging, etc., that raises your heart rate to the target range within 20 minutes is a suitable exercise. You can monitor your heart rate during your workout by taking a minute break, taking a pulse and counting the number of heartbeats. In short, choose a form of exercise that you enjoy and stick with it with interest, and when you get bored with one form of exercise, you can continue the activity with a different form of exercise. But remember: five minutes of warm-up before the activity, and five minutes of relaxation at the end – otherwise you may hurt yourself, and pain is not good for sleep. Avoid over-exercising!