Active Voice: Does Exercise Protect Against Sleep Complaints During Middle Age?
By Rod K. Dishman, Ph.D., FACSM, and Shawn D. Youngstedt, Ph.D.
Professor Rod Dishman, Ph.D., FACSM, is an exercise scientist and is co-director of the Exercise Psychology Laboratory at the University of Georgia in Athens. One of his research lines has examined mental health outcomes associated with physical activity, focusing on neurobiological mechanisms. He chaired the mental health section of the scientific advisory committee for the federal 2008 Physical Activity Guidelines for Americans. He has been a member of ACSM since 1978. Professor Shawn Youngstedt, Ph.D., is a sleep scientist in the College of Nursing and Health Innovation and with the program in Exercise Science and Health Promotion, Arizona State University in Phoenix. His research has focused on morbidities and mortality associated with sleep problems and non-pharmacologic means of improving sleep and mental health. His group has conducted research on the effects of exercise and bright light on insomnia, sleep apnea and Posttraumatic Stress Disorder. He has been a member of ACSM since 1989.
This commentary presents the views of Drs. Dishman and Youngstedt on the topic of a research article which they and their colleagues published in the May 2015 issue of Medicine & Science in Sports & Exercise® (MSSE).
Poor sleep is a burden on public health. It is associated with medical conditions such as coronary heart disease, hypertension, obesity, diabetes and metabolic syndrome. Poor sleep also contributes to emotional distress and impairment of daytime function. Nearly one in four middle-aged adults in the U.S. say they recently had trouble falling or staying asleep, or sleeping too much. About half the people who seek treatment for sleep problems will be prescribed a drug that will have poor efficacy and adverse risks with long-term use. Many people who don’t seek treatment will purchase over-the-counter sleep aids or use alcohol to get to sleep at night. Neither is effective or healthy in the long run.
Trials of exercise training have shown improved reports of sleep quality and objective measures of better sleep in middle-aged adults who already complained of sleep problems. However, whether regular exercise protects against the onset of sleep problems hasn’t been studied much. The scientific advisory committee for the federal 2008 Physical Activity Guidelines for Americans concluded there was moderate evidence to support that physical activity improves sleep. However, the committee recommended that physical activity exposures and outcomes need to be measured frequently to properly examine change. None of the epidemiological studies included in their review had concurrently assessed objectively measured change in physical activity exposure and sequential measures of sleep outcome, or accounted for other risk factors that can vary across time to confound the association between physical inactivity and the odds of sleep disturbance.
Change in cardiorespiratory fitness during middle age provides a proxy measure of cumulative physical activity exposure. Our collaboration with Steven N. Blair, P.E.D., FACSM, now at the University of South Carolina, let us follow 7368 men and 1155 women from the Aerobics Center Longitudinal Study that had not complained of sleep problems, depression or anxiety at their first visit to the Dallas clinic. Cardiorespiratory fitness (minutes of graded treadmill endurance) was assessed then and at three subsequent clinic visits, each separated by an average of two to three years.
There were 784 incident cases of sleep complaints in men (11 percent) and 207 cases in women (18 percent). After adjustment for initial fitness, age, time between visits and other risk factors for poor sleep assessed at each visit, each minute decline in treadmill endurance between ages 51 to 56 (about one-half MET) increased the odds of incident sleep complaints by 2 percent in men and 1 percent in women. Odds were approximately 8 percent higher per minute decline in fitness among people with sleep complaints at two or three visits.
Said another way, the decline in fitness was less for those who never reported sleep complaints – for men, only about 6 percent and only about 4 percent for women. It was about 8 percent in incident cases of sleep complaints, i.e., an additional loss of about one-half minute of maximal treadmill time. That smaller decline observed for those without sleep complaints is an amount easily retained in most people by regular, moderate-to-vigorous physical activity consistent with ACSM recommendations for healthy physical activity. Although a large randomized trial is needed to determine how many cases of sleep complaints might be prevented by mitigating this decline in fitness, our results suggest that maintenance of cardiorespiratory fitness during middle age, when decline in fitness typically accelerates and risk of sleep problems is elevated, helps protect against the onset of sleep complaints made to a physician in both men and women.