Exercise Helps You Sleep
Keith L. Cavanaugh, M.D.
Have you noticed how you have not been as physically active or not sleeping as well this past year since the pandemic? While there can be a lot of reasons for both, you should know there is a direct relationship between exercise and sleep that may be at play.
Professional athletes are embracing the clear evidence that good sleep helps them excel in their sports. NBA MVP LeBron James, tennis legend Venus Williams, and NFL MVP Tom Brady agree that adequate sleep helps them perform better. See Sleep Makes Us Play Hard for more details on this topic. At the same time, being physically active will also help you sleep better.
Surveys consistently show a strong connection between exercise and improved sleep. One survey of adults in Finland found “exercise” was the “most important habit” in helping them fall asleep immediately or perceive good sleep quality; 1/3 of men and women said exercise was more important than reading or listening to music, taking a sauna or shower, maintaining a regular lifestyle, or other psychological factors (7% of men, 8% of women). Another survey found that over 80% of adults reported exercise helped them fall asleep, followed distantly by reading before bed. (1.)
Graph 1: Cortisol Levels in People with and without Insomnia.
People say exercise helps them sleep better, but do we know why? Yes.
When a person encounters a stressful situation -- like a pandemic -- it can trigger a cascade of stress hormones in the body by the Sympathetic Nervous System (think of this as the “gas pedal”). A stressful incident will make us step on the gas. It can make the heart pound, breathing quicken, muscles tense, and the body sweat. This reaction to stress is known as the "fight-or-flight" response because it evolved as a survival mechanism, enabling people and other mammals to react quickly to life-threatening, stressful situations. When a person experiences stress, the brain works through a series of actions that leads to release of cortisol, or “the stress hormone.” The body remains on high alert to confront the danger. When the threat passes, cortisol levels decrease. How? We use the Parasympathetic Nervous System (think of this as the "brake") to then dampen the stress response (for example, taking deep breaths).
While stressful episodes are often temporary, unfortunately for many they last longer (particularly of late). As a result, their cortisol levels remain high. Persistent elevation of cortisol is not good for the body, or your sleep. How does cortisol impact sleep? Studies have shown that elevated levels of cortisol have been found in people with insomnia (difficulty falling asleep). (2) (See Graph 1.)
So, how can you decrease cortisol levels and help tap on the brakes? Exercise.
People can use exercise to counter stress in several ways. Activities that calm your thoughts are important to help fall asleep. Exercise, as simple as going for a walk shortly after feeling stressed will help deepen breathing, relieve muscle tension, and improve sleep. Be aware that the intensity and timing of exercise may affect your ability to sleep. Low-intensity exercise helps decrease cortisol levels. (3) While late-night exercise is perceived as counterproductive, there is no strong research to support this claim. If you find yourself having difficulty sleeping right after heavy exercise before bed, however, consider changing the intensity and timing of your workout. Regardless, exercising as part of your daily routine will help you sleep better.
What are the best exercises for me? Check out these suggestions from the Harvard Medical School that go beyond treadmills, stationary bikes, and weight machines. (4)
Youngstedt, Shawn D., and Christopher E. Kline. "Epidemiology of exercise and sleep." Sleep and biological rhythms 4.3 (2006): 215-221.
Basta M, Chrousos GP, Vela-Bueno A, Vgontzas AN. CHRONIC INSOMNIA AND STRESS SYSTEM. Sleep Med Clin. 2007;2(2):279-291. doi:10.1016/j.jsmc.2007.04.002
Hill, E. E., et al. "Exercise and circulating cortisol levels: the intensity threshold effect." Journal of endocrinological investigation 31.7 (2008): 587-591.
Dr. Cavanaugh is a board-certified Pediatric Pulmonary Medicine doctor, who joined Children’s Respiratory and Critical Care Specialists (CRCCS), P.A. in 2009. He attended medical school at Loyola University – Stritch School of Medicine in the Chicago area in Maywood, Illinois. He moved to Minnesota in 1996 knowing only one person in the state. After completing his residency training at the University of Minnesota in Combined Internal Medicine & Pediatrics in 2000 and a year as Chief Resident at the VA Medical Center in Minneapolis, he went on to one of the premiere fellowship programs in the country at the University of Colorado and National Jewish Health to complete respective fellowships in Pediatric Pulmonary Medicine and Sleep Medicine. He was an Assistant Professor in Pediatric Pulmonary Medicine and the Associate Director of The Children’s Hospital Sleep Center at The Children’s Hospital in Aurora, Colorado before moving back to Minnesota in 2009. He was the Medical Director of The Sleep Center at Children’s Minnesota until 2017 until he stepped down to focus more on Pulmonary Medicine. He remains passionate about Sleep, particularly for children.