Gabe Mirkin, M.D.
Many fitness instructors give you bad advice when they tell you not to exercise within three hours of going to sleep. Only three controlled studies on the effect of exercising before going to sleep exist in the scientific literature. All show that exercising vigorously before going to bed does not interfere with sleep. The latest study from the University of California, San Diego, shows that 3 hours of vigorous pedaling at 70 percent of maximum oxygen uptake in very bright lights did not stop fit men from falling or staying asleep.
The old argument was that vigorous exercise raises causes your body to produce large amounts of its own stimulants, adrenalin and nor adrenalin, that make your heart beat rapidly, raise body temperature and prevent you from feeling tired. Now we learn that exercise helps to prevent disease, prolong life and make you feel good. So it is better to exercise when ever you can, even if it's just before you go to bed.