Associations between insomnia, sleep duration and poor work ability

The aim of this study was to examine the independent and joint effect of insomnia and objective sleep duration on poor work ability.

In this cross-sectional study, a total of 2820 Chinese manufacturing workers were categorized as insomnia patients and individuals with normal sleeping pattern by interview according to DSM-IV criteria. Sleep duration was classified into four categories: ≥7h, 6-7h, 5-6h, and <5h according to objective sleep duration of Watch-PAT-200 test. Work ability was assessed using the Chinese Work Ability Index (WAI) questionnaire. Regression analysis examined the independent and joint association of sleep duration and insomnia with poor work ability, after adjusting for various confounding factors.

Insomnia and objective short sleep duration were both independently associated with poor work ability. Compared with the normal sleeping and ≥7h sleep duration group, the highest risk of poor work ability was in the insomnia patients with <5h sleep duration [odds ratio (OR) 3.43, 95% confidence interval (CI) 1.87-5.23], followed by the individuals with insomnia who slept 5-6h (OR 2.03, 95% CI 1.42-2.67).

Insomnia and sleep duration in workers are both separately and together associated with increased risk of poor work ability. Objective sleep duration should be taken into consideration when assessing the work ability of people with insomnia.