The interaction of sleep characteristics and work-related stress in relation to the risk of dementia: findings from a Swedish cohort study.

Both psychosocial work stress and low sleep quality may increase the risk of dementia. However, it is unclear whether sleep duration and insomnia symptoms moderate the association between work-related stress and dementia. We aimed to investigate how sleep characteristics and work-related stress interact to affect dementia risk. A total of 19,369 dementia-free participants aged ≥ 46 from the Swedish National March Cohort were included. Job demands, job control, sleep duration and insomnia symptoms were assessed using questionnaires. The Incidence of dementia was documented in national registers. Multivariable Cox models were used to estimate hazard ratios (HR) and 95% confidence intervals (CIs). During a median follow-up of 19.2 years, 1,067 cases of dementia occurred. Low job control, either alone or in combination with low job demands, was associated with an increased risk of dementia compared to high job control or high control combined with high demands. Stratified analyses revealed that dementia risk was higher for individuals with low job demands compared to those with high job demands only among those with normal sleep duration (≥ 7 h) (HR 1.34, 95%CI: 1.06-1.69) and those without insomnia (HR 1.30, 95% CI: 1.06-1.58). A similar pattern was observed for job control. Additionally, passive jobs were linked to an increased risk of dementia compared to active jobs among individuals with normal sleep duration (HR 1.58, 95% CI: 1.15-2.16) and those without insomnia symptoms (HR 1.52, 95% CI: 1.16-1.99). The findings suggest that sleep duration and insomnia symptoms may influence the observed association between work-related stress and dementia, but further research is needed to confirm these interactions.