Insomnia and long sleep duration are risk factors for later work disability. The Hordaland Health Study

J Sleep Res. 2009 Mar;18(1):122-8. doi: 10.1111/j.1365-2869.2008.00697.x. Epub 2008 Oct 13.


Both insomnia and sleep duration have previously been linked with a range of adverse outcomes, but no studies have explored their relative effect on subsequent work disability. The aim of the present study was to investigate the contribution of insomnia versus sleep duration to later long-term work disability. Using a historical cohort design with 4-year follow-up, data on insomnia, sleep duration and potential confounders were gathered from 6599 working persons (40-45 years). The outcome was award of disability pension, as registered in the National Insurance Administration. After controlling for baseline exposure to disability and sick leave, insomnia was a strong predictor of permanent work disability [odds ratio (OR) = 4.56], and this effect remained significant after controlling for sleep duration, as well as for other possible confounders (OR = 1.88). Short sleep duration was not significantly associated with subsequent work disability, while long sleep duration (>8.5 h) did predict work disability (OR = 2.96), also in the fully adjusted model (OR = 2.14).The present study demonstrates that both insomnia and long sleep duration are strong and independent risk factors for subsequent work disability.

MeSH terms

  • Adult
  • Cohort Studies
  • Disability Evaluation*
  • Disorders of Excessive Somnolence / complications*
  • Disorders of Excessive Somnolence / epidemiology
  • Female
  • Health Surveys
  • Humans
  • Male
  • Middle Aged
  • Norway
  • Odds Ratio
  • Retrospective Studies
  • Risk Factors
  • Sleep Initiation and Maintenance Disorders / complications*
  • Sleep Initiation and Maintenance Disorders / epidemiology
  • Social Security*
  • Statistics as Topic