Gender differences in nighttime sleep and daytime napping as predictors of mortality in older adults: the Rancho Bernardo study

Sleep Med. 2013 Jan;14(1):12-9. doi: 10.1016/j.sleep.2012.06.004. Epub 2012 Aug 28.


Objective: Many studies suggest optimal sleep duration for survival is 7-8h/night. We report the gender-specific independent association of all-cause mortality with nighttime sleep and daytime nap duration in older adults who were followed for up to 19years.

Methods: Between 1984 and 1987, 2001 community-dwelling, mostly retired, adults (1112 women), age 60-96years, answered questions about health, mood, medications, life-style, daytime napping, and nighttime sleep duration. Vital status was confirmed for 96% through July 2001.

Results: At baseline, men reported significantly longer nighttime sleep and daytime napping than women. In both men and women, nighttime sleep <6h was associated with depressed mood and sleep-related medication, and ⩾9h was associated with more alcohol consumption. Napping ⩾30min was associated with prevalent depressed mood, coronary heart disease, and cancer. Of the group, 61% died over the next 19years, at an average age of 85.6years. Mortality risk was lowest among those sleeping 7-7.9h/night in both men and women. Multiple-adjusted analyses showed that increased mortality was associated with nighttime sleep ⩾9h in women (HR 1.51: 95% CI=1.05-2.18), and with daytime napping ⩾30min in men (HR 1.28: 95% CI, 1.00-1.64).

Conclusions: Mechanisms for these differences are unknown.

Publication types

  • Research Support, N.I.H., Extramural

MeSH terms

  • Age Factors
  • Aged
  • Aged, 80 and over
  • Female
  • Humans
  • Male
  • Middle Aged
  • Mortality*
  • Risk Factors
  • Sex Factors
  • Sleep* / physiology
  • Time Factors