HONG, S., and J. E. DIMSDALE. Physical Activity and Perception of Energy and Fatigue in Obstructive Sleep Apnea. Med. Sci. Sports Exerc., Vol. 35, No. 7, pp. 1088-1092, 2003.
Purpose: This study was designed to examine the relationship between apnea severity, physical activity level, and psychological well being in patients with obstructive sleep apnea (OSA).
Methods: Participants' sleep, subjective report of psychological well-being, and physical activity level were assessed. Thirty-eight patients with sleep apnea (mean age 49.0 ± 8.9 yr; mean body mass index (BMI) 30.1 ± 4.9 (kg·m-2) with respiratory disturbance index [RDI] ≥ 10 were admitted to the study. Sleep architecture, subjective well-being, and self-reported habitual physical activity were measured.
Results: Sleep apnea severity (determined by RDI) was unrelated to subjective self-report of well-being. On the other hand, regular physical activity was significantly correlated with higher SF-36 vitality (rs = 0.54), higher Profile of Mood States vigor (rs = 0.41), and less fatigue (rs = -0.46). The association between physical activity and subjective well being remained significant even after controlling for RDI or BMI. In this group of subjects with sleep apnea, physical activity level was better than sleep apnea severity (i.e., RDI) in predicting perceptions of energy and fatigue.
Conclusion: The clinical significance of promoting regular physical activity or exercise training as an adjuvant treatment for OSA needs to be further investigated.
Exercise researchers have devoted relatively little attention to the relationship between exercise and sleep disorders (3,28). One of the most common sleep disorders is obstructive sleep apnea (OSA). This paper examines how self-reported physical activity level and sleep apnea severity are related to subjective well being in a sample of patients with OSA.
OSA is a disorder characterized by repetitive episodes of breathing cessation during sleep that leads to poor quality of sleep. Individuals with OSA frequently report subjective distress and poor quality of life in general (1,6), even after adjustments for body mass index (BMI), age, gender, and comorbidity (27).
Physical inactivity may be associated with the risk factors (e.g., obesity) contributing to severe sleep apnea (18). It is conceivable that patients with sleep apnea are neither psychologically motivated nor physically able to engage in regular exercise due in part to fatigue and daytime sleepiness. However, the relation between psychological well being and physical activity or exercise capability among patients with OSA is not known.
Physical activity might promote well being in patients with sleep apnea by improving sleep architecture. The effects of exercise or fitness on sleep have been studied extensively. Epidemiological (21,25), cross-sectional (20), and experimental (24,13) studies have suggested that both acute and chronic exercise influence sleep. Meta-analytic review of the literature revealed that acute exercise was associated with increased slow wave sleep (SWS), rapid eye movement (REM) sleep latency, total sleep time, and decreased REM sleep with effect sizes (g) ranging 0.18 to 0.52 (30) in healthy sleepers.
In addition to experimental results with smaller samples, population-based surveys also suggest that physical activity impacts sleep. Thirty percent of a thousand people surveyed in Finland responded that exercise was the most important factor in influencing their sleep. These individuals also indicated that their daytime tiredness was negatively related to weekly frequency of exercise (25). Another large survey conducted by Sherrill et al. (21) in the United States reported similar findings to the effect that regular physical activity or exercise was associated with less self-reported sleep disturbance (i.e., daytime sleepiness, disorders in initiating and maintaining sleep, and nightmares). Aerobically trained individuals report shorter sleep-onset latency and less tiredness in the morning and show longer SWS (20,24). However, the existing literature on exercise and sleep focuses primarily on sleep in healthy individuals with normal sleep; there is relatively little known on the effects of exercise among patients with sleep disorders.
The benefits of exercise and fitness in improving subjective sleep quality are documented, and there is a reasonable assumption that regular physical activity or exercise has therapeutic effects for OSA. However, studies investigating the effects of regular exercise or fitness on sleep or psychological health in sleep apnea patients are sparse. A few studies with limited sample sizes (i.e., 9-11) showed the effects of exercise (5,12) or healthy lifestyle (15,23) on symptoms of OSA. However, it is unclear whether aerobic fitness or regular physical activity has a direct influence on psychological states or indirect effects by affecting other risk factors (e.g., obesity, hypertension, etc.) associated with OSA. Individuals with OSA showed significantly reduced respiratory disturbance index (RDI) with increased total sleep time, decreased awakenings and arousals during sleep, and improved mood after 6 months of a supervised exercise program. Improved sleep and mood in those individuals were accompanied by decreased body weight and improved exercise tolerance (12). However, body weight and physical status in another group of OSA patients did not change after a 6-month exercise program in spite of reduced RDI and perceptions of improved energy and decreased fatigue (5).
This study investigated the relation between sleep apnea severity, self-reported regular physical activity, and psychological well being in OSA patients without other major comorbidity.