Sleeping can help to prevent exercise injuries. Healthy U.S. soldiers in training are less likely to suffer exercise-related injuries such as fractures, sprains and muscle strains when they sleep at least eight hours at night (Sleep Health, February 13, 2020). Compared to soldiers who slept eight hours a night, those who slept for fewer than five hours a night suffered double the rate of injuries. The average college athlete gets 6.5-7.2 hours of sleep each night (J Sci Med Sport, 2014;18), and increasing their sleep duration to eight or more hours per night improves performance in many different sports (Sleep, 2011 Jul 1; 34(7): 943-950).

Athletes who train for competition in sports that require endurance learn sooner or later that after exercising long and hard, they feel sleepy and need to go to sleep to recover (Eur J Sport Sci, 2008;8:119-126). Older people may need even more sleep after intense exercise than younger people. If you don’t get lots of extra sleep when you do prolonged intense exercise, you don’t recover as quickly and are at increased risk for injuring yourself. It works both ways: regular prolonged exercise helps insomniacs fall asleep more quickly (Sleep Med, 2011;12(10):1018-27; 2010;11(9):934-40). Sleep is necessary for healing your brain and your muscles (Front Physiol, 2014 Feb 3;5:24). You sleep to catch up on the energy that you lose being awake, both moving and thinking. Your brain uses more than 20 percent of your total energy, and the energy supply to your brain and nerves is regulated to a large degree by a chemical called ATP (Front Neur, Dec 27, 2011;2:87). When you are sleep deprived, levels of ATP drop (Prog Neurobiol, 2011;95:229-274), and when you go to sleep, brain levels of ATP rise significantly (J Neurosci, 2010;30:9007-9016).

Get Off Your Feet
• Athletes in intense training recover faster by getting off their feet after they finish their hard workouts and not even walking around until it is time for the next day’s recovery workout.
• Intense exercise damages muscles, which causes your pituitary gland to produce large amounts of human growth hormone (HGH) that helps to repair injured tissues, and you produce the largest amounts of HGH when you sleep. A ninety-minute recovery nap after you exercise also improves your ability to reason and think (Sleep, April 12, 2019;42(1):A71-A72).
• Runners who slept after a morning workout were able to run much faster all out in the evening (European Journal of Sport Science, May 31, 2018;18(9):1177-1184).
• Napping for more than 20 min after exercising improves mental preparation for subsequent performance (Sports Med, 2018;48:683-703).

Excessive Napping Can Signal Health Problems
Napping is healthful unless a person’s brain or heart is damaged so they require a lot of extra sleep (Heart, Sep 2019;105(23):1793-1798). People who take naps lasting longer than two hours are far more likely to suffer serious heart disease than those who take shorter naps or no naps at all (Sleep, 2015;38:1945-53), and people who nap longer than two hours have increased risk for diabetes as well as for heart attacks (Sci Rep, 2016;6:1-10). Excessive total sleep time appears to be a marker for serious heart disease and brain disease. Those who take daytime naps in addition to sleeping more than six hours every night are more likely to suffer heart attacks than nappers who sleep less than six hours at night (Eur Heart J, 2019;40:1-10). See my recent report, Is Napping Healthful?

Signs of Overtraining
A regular exercise program is supposed to make you feel good, increase your energy level, and help to control your weight, but exercising too much can affect your brain as well as your muscles. Athletes and dedicated exercisers often suffer from an overtraining syndrome in which their performance drops, their muscles feel sore and they are tired all the time. You may be exercising too much if you:
• feel irritable, tired during the day and unable to sleep at night
• lose your appetite
• see no improvement in your athletic performance over an extended time
• feel no enjoyment from exercising
• have frequent colds
• have persistent muscle soreness
In particular, muscle soreness on one side of your body or localized discomfort in one part of your body are major signs of an impending injury. For my personal story of overtraining syndrome, see Avoiding Overtraining

My Recommendations
Getting enough sleep is just one of the keys to recovery from intense exercise.
• Immediately after a hard workout, eat whatever sources of carbohydrates and protein you like best. I eat oranges and nuts to help me recover faster for my next workout.
• When you are training properly, your muscles can feel sore every morning. If they don’t feel better after a 10 minute warmup, take the day off.
• If you feel pain in one spot that does not go away during a workout, stop that workout immediately. Otherwise, you are likely to be headed for an injury.
For more of my recommendations, see Recovery: the Key to Improvement in Your Sport

Caution: Before you start or increase the intensity or duration of your exercise program, check with your doctor to make sure that you do not have any health conditions that may be harmed by vigorous exercise.