Focus on Fitness: Exercise and Sleep - Today's Dietitian Magazine

April 2020 Issue

Focus on Fitness: Exercise and Sleep
By Jennifer Van Pelt, MA
Today’s Dietitian
Vol. 22, No. 4, P. 50

The Centers for Disease Control and Prevention (CDC) recently called insufficient sleep a public health epidemic, based on statistics that showed increasing numbers of Americans losing sleep due to busy schedules, insomnia, sleep apnea, and other sleep disorders. For adults, at least seven hours per night is required for optimal health. The most current CDC statistics estimate that 70 million Americans have sleep duration–reducing chronic sleep problems due to chronic conditions that may negatively affect overall health. A section of the CDC’s website is devoted to tracking sleep-related statistics and increasing awareness of the importance of sleep. The CDC reports the following1:

• Lack of sufficient sleep is associated with increased injuries. For example, inadequate sleep can cause accidents while driving and working.
• Insufficient sleep contributes to a higher risk of chronic conditions and mental health issues, and decreased quality of life.
• Sleep problems have resulted in significant health care costs and lost work productivity.
• Adults who sleep less than seven hours per 24-hour period (dubbed “short sleepers”) are more likely to be physically inactive, smoke, and drink excessive alcohol when compared with adults who sleep seven or more hours.
• Short sleepers are more likely to have one or more chronic health issues, including heart disease, asthma, cancer, obesity, depression, arthritis, chronic kidney disease, and diabetes.
• Insomnia is the most common sleep disorder; short-term insomnia is reported by approximately 30% of adults, and chronic insomnia affects roughly 10%.
• Approximately 25 million adults have obstructive sleep apnea that affects sleep quality and duration.

It’s unclear whether there’s a circular or back-and-forth relationship between chronic health conditions and sleep. Does lack of sleep cause or exacerbate a chronic condition, or does the chronic condition make it difficult to sleep, or are both the case? A review of sleep research suggests a bidirectional relationship between exercise and sleep—exercise promotes better sleep, but poor sleep contributes to lack of exercise. Chronic conditions can make it even more difficult to exercise regularly. Researchers noted that “intervening on physical activity levels has been shown to improve sleep, but improving sleep has not resulted in increased levels of physical activity.”2 Increasing regular exercise in those with poor sleep quality isn’t as simple as improving sleep; clients with sleep issues may require additional motivation and behavior change to begin and maintain an exercise program.

The CDC, National Sleep Foundation (NSF), and American Academy of Sleep Medicine all recommend regular daily exercise to improve sleep.1,3,4 Even a small amount of light exercise helps to improve sleep. A survey on sleep and exercise habits conducted by the NSF found the following3:

• Exercisers reported better sleep than nonexercisers, even when they documented the same nightly sleep duration.

• Although vigorous, moderate, and light exercise all improved sleep, vigorous exercisers were twice as likely as nonexercisers to report a good night’s sleep almost every night and were least likely to report sleep problems, such as difficulty falling asleep and waking up from sleep during the night.

• Exercise at any time during the day was good for sleep. A common belief is that vigorous exercise later in the evening will disrupt sleep by stimulating the body and raising body temperature. Only 3% of evening exercisers reported worse sleep due to exercise. More than 50% of those who performed vigorous or moderate exercise in the evening (within four hours of bedtime) reported sleeping better. These survey results led to the NSF changing recommendations on timing of exercise relative to sleep; exercise at any time of the day is recommended, as long as sleep isn’t disrupted. Avoiding late evening and night exercise is suggested for those with chronic insomnia, and morning or afternoon exercise is recommended instead.

• Decreasing time spent sitting improves sleep quality. Those who reported sitting for less than eight hours daily were twice as likely to report very good sleep quality than those who reported sitting for more than eight hours.

• Nonexercisers reported being “excessively sleepy” more than exercisers and had more symptoms of sleep apnea than those who exercised regularly. The survey data showed that risk of sleep apnea in exercisers was half that of nonexercisers. Regular exercise is especially beneficial for those with sleep apnea, which often is caused by obesity. Just a small amount of weight loss can improve sleep apnea symptoms.

What types of exercise are best for improving sleep? Based on the results of the NSF survey, the answer might be “all types.” Improving sleep for a sedentary client may involve just a 10-minute walk daily, or even simply setting reminders to get up from sitting and moving every hour for a few minutes. Aerobic exercise and resistance training have been studied and found to improve sleep. A 2018 systematic review found that regular resistance training improved sleep quality, and, when it was combined with aerobic exercise, benefits increased.5 A 2012 systematic review found that either moderate-intensity aerobic exercise or high-intensity resistance training significantly improved sleep.6 Various forms of mind-body exercise, including yoga, tai chi, and qigong, also have been found to improve sleep in those with certain medical conditions (research studies are too numerous to cite).

So, the type of exercise primarily depends on the individual and the factors that may be contributing to poor sleep. All exercisers, especially those who exercise later in the day, should consider tracking sleep quality to detect any patterns. While survey results showed a majority of exercisers weren’t affected by the time of day they exercised, some may have sleep disrupted by late evening physical activity. Sleep disruption from later exercise also may be linked to the type of exercise. For example, I’ve found that I can do vigorous yoga within two hours of bedtime and sleep fine, but, if I do an aerobic workout close to bedtime, I have trouble winding down and going to sleep. Those with chronic pain may find that certain types of exercise aggravate pain and further disrupt sleep and may need to limit exercise to low-impact aerobics, light resistance training, and/or gentle mind-body exercise.

— Jennifer Van Pelt, MA, is a certified group fitness instructor and health care researcher in the Lancaster, Pennsylvania, area.

References
1. Sleep and sleep disorders. Centers for Disease Control and Prevention website. https://www.cdc.gov/sleep/index.html. Updated February 22, 2018.

2. Kline CE. The bidirectional relationship between exercise and sleep: implications for exercise adherence and sleep improvement. Am J Lifestyle Med. 2014;8(6):375-379.

3. National Sleep Foundation poll finds exercise key to good sleep. National Sleep Foundation website. https://www.sleepfoundation.org/press-release/national-sleep-foundation-poll-finds-exercise-key-good-sleep

4. Research notes: 5 surprising facts about exercise and sleep. American Academy of Sleep Medicine website. https://aasm.org/research-notes-5-surprising-facts-about-exercise-and-sleep/. Published February 26, 2013.

5. Kovacevic A, Mavros Y, Heisz JJ, Fiatarone Singh MA. The effect of resistance exercise on sleep: a systematic review of randomized controlled trials. Sleep Med Rev. 2018;39:52-68.

6. Yang PY, Ho KH, Chen HC, Chien MY. Exercise training improves sleep quality in middle-aged and older adults with sleep problems: a systematic review. J Physiother. 2012;58(3):157-163.