Ask the Sleep Experts

Your questions about sleep and sleep disorders answered by our issue reviewers who are sleep specialists with a combined 64 years of experience in the field of sleep medicine.  Have a question for the sleep experts? Submit questions to  Questions are selected based on space and applicability.

Does exercise improve sleep?

Dr. Ramagopal:

In general exercise does help people achieve better quality sleep. Exercise increases the core body temperature, and the temperature dropping after exercise mimics what happens before sleep onset, telling the brain it is time for rest. Over time, moderate aerobic exercise increases total sleep time, sleep latency onset, and the amount of slow wave sleep. This supports memory consolidation, mind-body rejuvenation, and growth hormone secretion, which is especially important for children.

Dr. Thomas:

There is some data that a moderate workout two to three hours before bedtime can be beneficial. Exercise too close to bedtime can cause sleep disruption. Other approaches to optimize sleep (e.g., consistent wake up time, strong and regular light/dark cycle, relaxing before bedtime) may be more reliable. There can be trial and error to tailor exercise time and intensity for an individual. Exercise does improve general fitness and quality of life, so there is an indirect benefit to sleep. As answered by our issue reviewers

Should I work out if I feel tired?

Dr. Thomas:

Gentle working out is fine, but an exhausting program will amplify fatigue. Of course, the cause of tiredness matters. If it is transient, like an overnight shift, do what you can. If chronic or part of a fatigue disorder (e.g. long Covid), or post-exertional malaise – symptoms can worsen. Knowing your limits is important. It is usually difficult to do a strenuous program when sleep deprived.

Dr. Ramagopal:

As tempting as it is to skip working out when feeling tired, increasing physical activity has benefits. Exercise releases endorphins which help relieve pain, stress, and can improve the quality of sleep. Additionally, exercise releases serotonin, which is a precursor to melatonin, the main hormone involved in sleep onset. However, if there is a medical condition that is causing chronic fatigue, address this condition first.

How does the time of day I work out affect my ability to sleep?

Dr. Ramagopal: This depends on one’s schedule. There is no “bad time” to exercise, but consistency is key. Physiologically speaking, before 7 am is the best time to exercise. The elevated levels of cortisol and growth hormone in the morning stimulate gluconeogenesis, which is a metabolic process by which the body synthesizes glucose from non-carbohydrate precursors like fats and proteins and maintains glucose homeostasis. This process is helpful for weight loss. This time may not work for shift workers, so doing some form of cardiovascular activity prior to the start of a shift may be helpful. Strenuous exercise within two hours of bedtime may cause a shift in the circadian rhythm and delay sleep onset. A low-intensity activity like stretching or yoga is less likely to affect sleep onset.

Dr. Thomas: If the workout is part of insomnia/circadian management, then exposure to light should determine the “zone” of the engagement. For example, if there is a need for morning light exposure, then morning is best. Often, your schedule and responsibilities determine the best time to exercise. If you have a long commute, early morning may not be practical. It makes sense to avoid a workout just after a major meal since it can be uncomfortable to have a large meal bouncing in the stomach. Insulin-dependent diabetics will have a complex protocol of what to do when, and not.

Have a question for the sleep experts? Submit questions to Questions are selected based on space and applicability.

Maya Ramagopal, MD is a Pulmonologist and Sleep Medicine Specialist at the Robert Wood Johnson University Hospital in New Brunswick, New Jersey. She is the Medical Director of the Pediatric Program at the Comprehensive Sleep Disorders Center and Professor at Rutgers Robert Wood Johnson Medical School. She has been in sleep medicine for 15 years.

Robert J. Thomas, MD is a Professor of Medicine at Harvard Medical School and is associated with Beth Israel Deaconess Medical Center, Boston, Massachusetts. He has been in the field of sleep medicine for 28 years.



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