Rest/activity rhythms and mortality rates in older men: MROS sleep study

An association between increased risk of mortality and disruptions in restactivity circadian rhythms (RAR) has been shown among adults with dementia and with metastatic colorectal cancer. However, the association among a more general population of older adults has not been studied. Our study population consisted of 2964 men aged≥67 yrs of age enrolled in the Outcomes of Sleep Disorders in Older Men (MrOS Sleep) Study. Restactivity patterns were measured with wrist actigraphy. RAR parameters were computed and expressed as quintiles, and included acrophase (time of peak activity level), amplitude (peak-to-nadir difference), mesor (middle of the peak), pseudo F-value (overall circadian rhythmicity), beta (steepness), and alpha (peak-to-trough width). After adjustment for multiple potential confounders, men in the lowest quintile of pseudo F-value had a 57 higher mortality rate (hazard ratio [HR] = 1.57, 95 CI, 1.03-2.39) than men in the highest quintile. This association was even stronger with increased risk of cardiovascular disease-related mortality (CVD) (HR = 2.32, 95 CI, 1.04-5.22). Additionally, men in the lowest quintile of acrophase had a 2.8-fold higher rate of CVD-related mortality (HR = 2.84, 95 CI, 1.29-6.24). There was no evidence of independent associations with amplitude, mesor, alpha, beta, and mortality risk. Older men with less robust RAR and earlier acrophase timing have modestly higher all-cause and CVD-related mortality rates. Further research should examine potential biological mechanisms underlying this association.