Association between insomnia symptoms and chronotype—A systematic review and meta-analysis

This meta-analysis aimed to examine the association between chronotype and insomnia. A systematic search of PubMed, Embase, and the Cochrane Library was conducted to identify prospective and cross-sectional studies published before July 2023. Sixteen studies involving 27,789 participants were included. Chronotype was assessed using the Morningness-Eveningness Questionnaire. Odds ratios with 95% confidence intervals were calculated for dichotomous outcomes, and mean differences with 95% confidence intervals were used for continuous outcomes. Random-effects models were applied in the presence of moderate-to-high heterogeneity. Sensitivity and subgroup analyses were performed to assess robustness and consistency. Compared with morning types, evening chronotypes had a significantly higher risk of insomnia (odds ratio, 3.47; 95% confidence interval, 2.50-4.83; P<.00001) and higher ISI scores (mean difference, 3.00; 95% confidence interval, 1.70-4.30; P<.00001). Intermediate chronotypes also showed elevated risk (odds ratio, 1.61; 95% confidence interval, 1.24-2.09; P=.0004) and moderately higher ISI scores (mean difference, 1.55; 95% confidence interval, 0.47-2.63; P=.005) compared with morning types. Individuals with an evening chronotype were more likely to report insomnia symptoms compared with those with morning or intermediate chronotypes. Intermediate chronotypes tended to have a moderate association, while morning types showed the lowest likelihood of reporting insomnia symptoms. These findings highlight the importance of considering chronotype in the assessment and management of insomnia.