Insufficient sleep is a known risk factor for obesity related-diseases, depression and mortality, and it can cause socioeconomic damage by decreasing daytime production. Although some studies reported a positive association between habitual physical activity and better sleep, there have been few prospective cohort studies examining this relationship. The purpose of this study is to investigate whether physical activity prevents the future development of short sleep duration and poor sleep quality. We collected survey data from annual health check-ups conducted in 2008 in Tokyo, Japan. After excluding participants who reported short sleep duration and/or poor sleep quality at baseline, there were 6185 analysis participants. Our study followed participants until short sleep duration or poor sleep quality had been reported or until the end of 2012. We followed participants an average of 2.8 years（ 17194 person-years） in which 1632 of 6185 people reported short sleep duration and/or poor sleep quality. A multivariable-adjusted Cox proportional hazards model showed that low-intensity（ HR=0.86, 95% CI=0.75–0.97） or vigorous-intensity（ HR=0.81, 95% CI=0.67–0.97） physical activity performed at least once per week significantly reduced incident short sleep duration compared with no physical activity. Engaging in moderate-intensity physical activity（ HR=0.87, 95% CI=0.70–1.07） also decreased risk of short sleep duration, but this was not significant. Lowintensity（HR=0.80, 95% CI=0.70–0.91）, moderate-intensity（ HR=0.80, 95% CI=0.64–1.00） and vigorous-intensity（HR=0.74, 95% CI=0.61–0.90） physical activity also significantly reduced incident poor sleep quality. When looking at the combination variable of short sleep duration and poor sleep quality, people who engaged in low-intensity（HR=0.84, 95% CI=0.76–0.93）, moderate-intensity（ HR=0.85, 95% CI=0.72–1.00） and vigorous-intensity （HR=0.79, 95% CI=0.68–0.91） physical activity had a significantly ecreased risk of insufficient sleep. Our results suggest that physical activity, regardless of intensity levels, can reduce future incident short sleep duration and poor sleep quality.
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