Many fitness instructors give bad advice when they tell you not to exercise within three hours before going to sleep. Several studies show that exercising vigorously before going to bed does not interfere with sleep. One study from the University of California at San Diego showed that three 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 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. Newer studies show that doesn’t happen. We also know that exercise helps to prevent disease, prolong life and make you feel good. So it is better to exercise whenever it’s convenient for you, even if it’s just before you go to bed.