Sleep duration, mortality and the influence of age.

Area of Science:

• Gerontology
• Epidemiology
• Sleep Medicine

Background:

• Previous research indicates both short and long sleep durations are associated with increased mortality.
• Sleep duration naturally declines with advancing age, potentially altering its relationship with mortality.
• Understanding how age modifies the sleep-mortality link is crucial for public health.

Purpose of the Study:

• To investigate whether the association between sleep duration and mortality differs across age groups.
• To determine if age moderates the impact of sleep duration on all-cause mortality.

Main Methods:

• A prospective cohort study involving 43,863 participants (64% women) recruited in 1997.
• Sleep duration was self-reported using the Karolinska Sleep Questionnaire and categorized as ≤5, 6, 7 (reference), or ≥8 hours.
• Mortality data were collected via record linkage up to 2010, with analysis using multivariable Cox proportional hazards regression.

Main Results:

• Among individuals younger than 65 years, both short (≤5 hours) and long (≥8 hours) sleep durations were significantly associated with increased mortality (HR 1.37 and 1.27, respectively).
• In contrast, no significant relationship between sleep duration and mortality was observed in individuals aged 65 years or older.
• The mortality risk associated with extreme sleep durations was most pronounced in younger individuals and decreased progressively with age.

Conclusions:

• Age significantly modifies the relationship between sleep duration and mortality.
• The detrimental effects of short and long sleep on mortality are primarily evident in younger and middle-aged populations.
• Sleep duration may be a less critical predictor of mortality in older adults compared to younger individuals.