Joint association of physical activity and sleep difficulties with the incidence of hypertension in mid-age Australian women

Introduction: Little is known about the joint effects of physical activity and sleep difficulties on hypertension. The aim of this study was to examine the joint associations of physical activity and sleep difficulties with the incidence of hypertension in mid-aged women. Study Design: Prospective cohort study. Main Outcome Measures: Mid-aged participants (n = 5,300) in the Australian Longitudinal Study on Women's Health completed four triennial surveys starting in 2004, when they had a mean age of 55 years. The presence of hypertension, physical activity and the number of sleep difficulties (range 0-4) were reported at each survey. Total MET.min/week of physical activity was assessed, and dichotomised as inactive (<500 MET.min/wk) or active (≥500 MET.min/wk). Joint categories of physical activity and sleep difficulties were created using six mutually exclusive groups. Associations of joint physical activity and sleep difficulty groups with incident hypertension were examined via discrete-time survival analysis using logit-hazard models. Results: There were 1,175 cases of incident hypertension (22.2%). Compared with the Active and No Difficulties group, women in the Inactive and 1 Difficulty (Odds Ratio (95% confidence interval) (1.31 (1.06, 1.62)) and Inactive and 2-4 Difficulties (1.44 (1.16, 1.78)) groups were more likely to develop hypertension. Sleep difficulties were not associated with hypertension among active women. Conclusions: Mid-aged inactive women with sleep difficulties were more likely to develop hypertension. Physical activity appeared to protect against the increased risk of hypertension in women with sleeping difficulties.