Hours lying down per day and mortality from all-causes and cardiovascular disease: the HUNT Study, Norway

Time spent sitting has been positively associated with mortality in several studies, whereas time lying down per day has not been extensively studied. The authors prospectively examined the association between hours lying down per day and risk of death from all-causes and from cardiovascular disease among 39,175 persons aged 20-79 years in the population-based HUNT Study in Norway. Adjusted hazard ratios (HRs) with 95 % confidence intervals (CIs) were obtained from Cox regression, using people lying down for 7 h per day as reference. During a median follow-up of 12.3 years a total of 2,659 persons died (851 from cardiovascular disease). People lying 11-18 h per day had a HR of 1.60 (95 % CI 1.29, 1.98) for death from all causes and a HR of 1.91 (95 % CI 1.35, 2.71) for cardiovascular death. Analyses stratified by leisure time physical activity showed a positive association with cardiovascular mortality also among physically active people, with HRs of 1.38 (95 % CI 0.97, 1.96) and 1.84 (95 % CI 1.07, 3.16) among people lying down 10 and 11-18 h per day, respectively. In this large prospective study, excessive hours lying down per day were associated with increased all-cause and cardiovascular mortality, even among physically active persons.