Sleep And Exercise

The relationship between physical activity and sleep is complex, but understanding the connections between the two is important if you want to improve the quality of your sleep. Deep sleep is necessary for physical restoration. During deep sleep, the secretion of growth hormone reaches its daily peak, and in adults this hormone is responsible for tissue repair and renewal. Resting quietly in bed, awake, one is not able to achieve the same restorative function. Even sleeping lightly (in twilight-zone sleep) for extended periods does not achieve the same recovery. Accordingly, you would expect increased amounts of deep sleep after exercise, and this certainly is true in many cases - for example, marathon runners have a substantial increase in deep sleep on the evening after their event. Mild exercise, such as housework, bowling, or other light physical exertion, does not seem to make any difference to the subsequent amount of deep sleep. It appears that there is some threshold amount of energy that must be expended before the benefits of exercise are seen. These benefits include allowing you to go to sleep more quickly, increasing the amount of deep sleep, and reducing the number of awakenings throughout the night. Good exercise makes you sleep better, and good sleep allows you to recover.   

The benefits of exercise are not seen, however, if exercise is taken at the wrong time in relation to sleep. Essentially, you must time your exercise well if you want it to help you to sleep. Moderate physical activity just before you try to go to sleep actually disturbs sleep by delaying the onset of sleep and increasing the number of awakenings throughout the night. Optimally, you must exercise no less than four hours before trying to sleep. The best time to exercise is during the day or early evening; your body temperature may well be the reason. 

Our body temperatures are not constant throughout the day; we have a built-in thermostat and our temperature increases to a maximum in mid-afternoon and then lowers very slowly to its minimum level at about four a.m. For most people, this change in temperature is just slightly less than one centigrade degree, though the change in temperature is less in seniors. We sleep better when our temperature is falling than when it is at its peak, or rising. Most good aerobic exercise will increase your core temperature by about one centigrade degree and, after recovery, the temperature slowly falls back to the usual for that time of day. It seems that exercise too close to bedtime means that the temperature is still elevated when you are trying to sleep, and that's why exercise four to six hours before bedtime is ideal. There is some individual variation, but the principle applies: exercise earlier in the day or evening is better than exercise just before sleep. This may explain why a hot bath helps you sleep: the same principle applies - an increase in body temperature with a slow fall. A hot bath is more conducive to sleep if it occurs not immediately before bedtime, but an hour or so before. 

Robert Hutchins, an American educator, wrote, "Whenever I feel like exercise I lie down until the feeling passes." Many people share his opinion, approaching exercise as if it were drudgery. The first rule of exercise is that you must change your attitude toward it. 

Exercise should be fun; the word our children use for it is play, and that is accurate. Ideally, exercise should be something that you enjoy, something that you look forward to and something that makes little demand on you mentally. It should be a stress-releasing time, not a stress-producing one. It should be a time for shedding the cares and worries of the day, when the mind is free to wander; it should not be an ordeal. The rhythmic movement of your body, especially outdoors, is an essential evolutionary requirement; that's what we as a species have been doing for millions of years. It's primal, and a basic human need. It's also fun. 

What's the best exercise for you? The answer is: many different activities. Don't set yourself up with a program of one single activity, such as jogging; no matter how much you think you enjoy it, if you do it frequently enough it will become tedious. Instead, develop an exercise schedule that involves doing many different activities. There is nothing more pleasing than mastering a new physical skill, such as canoeing or playing tennis or lawn bowling, no matter what your age. Explore those activities that you think you might like; you'll be surprised at the pleasure that accompanies learning a new sport. 

Ideal exercise is aerobic - that is, sustained and uninterrupted - and lasts for at least twenty minutes a day. Such activities as brisk walking, bicycling, jogging, aerobic exercise routines, skiing, swimming, and dancing qualify. Simple housework, garden work, or similar activities usually do not produce the sustained effort that qualifies as adequate exercise and improves your sleep pattern. If you look at your daily activity schedule with a view to increasing the amount of time you devote to exercise, you'll find that the twenty minutes a day is easily accommodated. Soon you'll discover that exercise is not a chore, but an enjoyable part of your life.