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Effects of a yearlong moderate-intensity exercise and a stretching intervention on sleep quality in postmenopausal
Shelley S Tworoger1, Yutaka Yasui, Michael V Vitiello
1The Fred Hutchinson Cancer Research Center, Division of Public Health Sciences, Cancer Prevention Research Program, Seattle, Wash 98109-1024, USA.
Study Objectives:
To examine the effects of a moderate-intensity exercise or stretching intervention and changes in fitness, body mass index, or time spent outdoors on self-reported sleep quality and to examine the relationship between the amount and timing of exercise and sleep quality.
Design:
A randomized intervention trial.
Setting:
A cancer research center in Seattle, Washington.
Participants:
Postmenopausal, overweight or obese, sedentary women not taking hormone replacement therapy, aged 50 to 75 years, and recruited from the Seattle metropolitan area.
Interventions:
A yearlong moderate-intensity exercise (n=87) and a low-intensity stretching (n=86) program.
Measurements And Results:
Among morning exercisers, those who exercised at least 225 minutes per week had less trouble falling asleep (odds ratio [OR]: 0.3, P < or = .05) compared with those who exercised less than 180 minutes per week. However, among evening exercisers, those who exercised at least 225 minutes per week had more trouble falling asleep (OR: 3.3, P < or = .05) compared to those who exercised less than 180 minutes per week. Stretchers were less likely to use sleep medication (OR = 0.4, P < or = .05) and have trouble falling asleep (OR: 0.7, P < or = .10) during the intervention period compared with baseline. A greater than 10% versus a 1% or less increase in maximum O2 consumption over the year was associated with longer sleep duration (P < or = .05), less frequently falling asleep during quiet activities (P < or = .05), and less use of sleep medication (P < or = .05). Reductions in body mass index and increases in time spent outdoors had inconsistent effects on sleep quality.
Conclusions:
Both stretching and exercise interventions may improve sleep quality in sedentary, overweight, postmenopausal women. Increased fitness was associated with improvements in sleep. However, the effect of moderate-intensity exercise may depend on the amount of exercise and time of day it is performed.