MINNEAPOLIS—A review of the current literature indicates that exercise can reduce the symptoms of insomnia, according to an overview presented at the 28th Annual Meeting of the Associated Professional Sleep Societies. Studies suggest that exercise has a generally positive effect on subjective sleep ratings, Pittsburgh Sleep Quality Index (PSQI), sleepiness, quality of life, sleep latency, wake after sleep onset, and sleep efficiency in particular. Most of the trials involved small patient populations, however.
Many questions about exercise’s effect on insomnia remain unanswered. Most of the relevant research has focused on middle-aged or older adults and “may be less relevant for younger adults who are perhaps more physically active,” said Phyllis Zee, MD, Benjamin and Virginia Boshes Professor of Neurology and Director of the Center for Circadian and Sleep Medicine at Northwestern University Feinberg School of Medicine in Chicago. In addition, no data shed light on the dose, duration, and type of exercise that are most effective for treating insomnia. Researchers also have not examined whether gender influences the effect of exercise on insomnia.
Exercise May Improve PSQI
Chronic insomnia often entails activation of the hypothalamic–pituitary–adrenal axis, autonomic activation, cognitive impairment, and mood disturbance. Data indicate that exercise improves these outcomes in people without insomnia, but fewer trials have analyzed whether exercise improves sleep in patients with insomnia.
Although several studies show that exercise improves sleep, particularly among older adults, and exercise is a common recommendation as part of good sleep hygiene, few studies have been conducted in patients with insomnia disorder. Recent studies show that exercise provides a modest improvement in subjective and objective sleep parameters in this population. The efficacy of exercise may be comparable to that of other treatments, including hypnotics, said Dr. Zee.
Researchers conducting a meta-analysis in 2012 found that most studies examining exercise’s effect on insomnia were not randomized or were otherwise ineligible for inclusion. The investigators identified five eligible studies, some of which did not include a control group.
Participants in the studies engaged in a minimum of 10 weeks of exercise. The meta-analysis concluded that exercise tends to improve PSQI and decrease sleep latency. The researchers could not reach a conclusion about exercise’s effect on wake after sleep onset (WASO) because not every study measured that outcome.
Exercise and Nonphysical Activity
Dr. Zee and colleagues conducted a trial that compared the effects of exercise and nonphysical activity in patients with insomnia. Eligible patients were 55 or older, had chronic insomnia, exercised twice per week or less, and did not have sleep apnea. At baseline, patients underwent three nights of PSG in a clinical research unit, as well as blood sampling every 30 minutes for 24 hours.
Patients were randomized to exercise and sleep hygiene education or to nonphysical activity and sleep hygiene education. Exercise consisted of three 30- to 45-minute sessions per week during which participants walked, swam, or performed other activities. Patients randomized to nonphysical activity engaged in outdoor structured activities, including social activities, four times per week.
The study lasted for 16 weeks, during which participants kept sleep diaries and were measured by actigraphy. Every two hours, for 12 hours per day, patients rated their global vigor, alertness, and global affect using visual analog scales. They responded to questionnaires at eight weeks. At 16 weeks, participants were readmitted to the clinical research unit and underwent the same polysomnogram and blood sampling protocol that had been administered at baseline.
A total of 16 patients (10 women) enrolled in the study. Participants’ mean age at baseline was 62, and the population was overweight, but not obese. Mean baseline PSQI was greater than 5, and all participants had sleep complaints.
Exercise Improved Subjective and Objective Sleep Measures
Exercise was associated with improvements in subjective sleep quality and daytime function. At week 16, PSQI was reduced significantly among patients randomized to exercise. Depression scale scores and daytime sleepiness also were reduced significantly in the exercise group. The results were “remarkable,” said Dr. Zee. “You may not actually see the decrease in sleepiness in a younger group,” she added.
Data analysis indicated that improvements in PSQI were mediated partially by improvements in depressive symptoms. Global vigor did not decrease during the afternoon among patients randomized to exercise as it did among controls. Alertness improved during the late afternoon in the exercise group, compared with controls. In addition, global affect was higher throughout the day for the exercise group than for the control group.
Sleep duration increased by approximately 45 minutes in the exercise group and by about 30 minutes among controls. “That’s a pretty good effect size for these types of trials, even if you look at the hypnotic literature,” said Dr. Zee. Actigraphy data showed that the effect of exercise on sleep duration was apparent at eight weeks.