title: Fragmentation and stability of circadian activity rhythms predict mortality: the Rotterdam study.
abstract: Circadian rhythms and sleep patterns change as people age. Little is known about the associations between circadian rhythms and mortality rates. We investigated whether 24-hour activity rhythms and sleep characteristics independently predicted mortality. Actigraphy was used to determine the stability and fragmentation of the 24-hour activity rhythm in 1,734 persons (aged 45-98 years) from the Rotterdam Study (2004-2013). Sleep was assessed objectively using actigraphy and subjectively using sleep diaries to estimate sleep duration, sleep onset latency, and waking after sleep onset. The mean follow-up time was 7.3 years; 154 participants (8.9%) died. Sleep measures were not related to mortality after adjustment for health parameters. In contrast, a more stable 24-hour activity rhythm was associated with a lower mortality risk (per 1 standard deviation, hazard ratio = 0.83, 95% confidence interval: 0.71, 0.96), and a more fragmented rhythm was associated with a higher mortality risk (per 1 standard deviation, hazard ratio = 1.22, 95% confidence interval: 1.04, 1.44). Low stability and high fragmentation of the 24-hour activity rhythm predicted all-cause mortality, whereas estimates from actigraphy and sleep diaries did not. Disturbed circadian activity rhythms reflect age-related alterations in the biological clock and could be an indicator of disease.
authors.forename: Lisette A
authors.initials: LA
authors.lastname: Zuurbier
authors.forename: Annemarie I
authors.initials: AI
authors.lastname: Luik
authors.forename: Albert
authors.initials: A
authors.lastname: Hofman
authors.forename: Oscar H
authors.initials: OH
authors.lastname: Franco
authors.forename: Eus J W
authors.initials: EJ
authors.lastname: Van Someren
authors.forename: Henning
authors.initials: H
authors.lastname: Tiemeier
mesh_terms: D056044:Actigraphy; D000368:Aged; D000369:Aged, 80 and over; D015984:Causality; D002940:Circadian Rhythm / Q000502:physiology*; D005260:Female; D006801:Humans; D008297:Male; D008875:Middle Aged; D009026:Mortality; D016016:Proportional Hazards Models; D011446:Prospective Studies; D012306:Risk; D012890:Sleep / Q000502:physiology*; D016019:Survival Analysis
keywords: circadian activity rhythm; elderly; mortality; sleep