Midlife sleep characteristics associated with late life cognitive function

Sleep. 2013 Oct 1;36(10):1533-41, 1541A. doi: 10.5665/sleep.3052.


Study objectives: Previous studies with limited follow-up times have suggested that sleep-related traits are associated with an increased risk of incident dementia or cognitive decline. We investigated the association between midlife sleep characteristics and late life cognitive function.

Design: A follow-up study with a median follow-up time of 22.5 (range 15.8-25.7) years assessing the association between midlife sleep characteristics and later cognitive function.

Setting: Questionnaire data from 1981 were used in the assessment of sleep characteristics, use of hypnotics, and covariates at baseline. Between 1999 and 2007, participants were assigned a linear cognitive score with a maximum score of 51 based on a telephone interview (mean score 38.3, SD 6.1). Linear regression analyses were controlled for age, sex, education, ApoE genotype, and follow-up time.

Participants: 2,336 members of the Finnish Twin cohort who were at least 65 years of age.

Interventions: N/A.

Measurements and results: Baseline short (< 7 h/day) and long (> 8 h/day) sleepers had lower cognitive scores than participants sleeping 7-8 h/ day (β = -0.84, P = 0.014 and β = -1.66, P < 0.001, respectively). As compared to good sleep quality, poor or rather poor sleep quality was associated with a lower cognitive score (β = -1.00, P = 0.011). Also, the use of hypnotics ≥ 60 days per year was associated with poorer cognitive function (β = -1.92, P = 0.002).

Conclusions: This is the first study indicating that midlife sleep length, sleep quality, and use of hypnotics are associated with late life cognitive function. Further confirmation is needed, but sleep-related characteristics may emerge as new risk factors for cognitive impairment.

Keywords: Cognition; cohort studies; hypnotics and sedatives; risk factors; sleep.

Publication types

  • Research Support, Non-U.S. Gov't
  • Twin Study

MeSH terms

  • Age Factors
  • Aged
  • Apolipoproteins E / genetics
  • Cognition / physiology*
  • Cognitive Dysfunction / etiology
  • Dementia / etiology
  • Diseases in Twins / physiopathology
  • Female
  • Follow-Up Studies
  • Genotype
  • Humans
  • Hypnotics and Sedatives / therapeutic use
  • Interviews as Topic
  • Male
  • Middle Aged
  • Neuropsychological Tests
  • Risk Factors
  • Sleep / physiology*
  • Sleep Wake Disorders / complications
  • Surveys and Questionnaires
  • Twins, Dizygotic
  • Twins, Monozygotic


  • Apolipoproteins E
  • Hypnotics and Sedatives