Sleep problems and risk of all-cause cognitive decline or dementia: an updated systematic review and meta-analysis

Objectives To conduct an updated systematic review and meta-analysis of association between sleep and all-cause cognitive disorders. Methods PubMed and EMBASE were searched from inception to 18 February 2019. Cohort studies exploring longitudinal associations of sleep with cognitive decline or dementia were included. The multivariable-adjusted effect estimates were pooled by random-effects models, with credibility assessment. The robusterror meta-regression model was used to conduct the dose-response meta-analysis for sleep duration. Results 11 155 reports were searched and 51 eligible cohorts with 15 sleep problems were included for our meta-analyses. Ten types of sleep conditions or parameters, including six (insomnia, fragmentation, daytime dysfunction, prolonged latency, rapid eye movement sleep behaviour disorder and excessive time in bed) with moderate-to-high levels of evidence, were linked to higher risk of all-cause cognitive disorders. Furthermore, a U-shaped relationship was revealed for the associations with sleep duration. Conclusions Sleep management might serve as a promising target for dementia prevention.