Insomnia and the risk of depression: a meta-analysis of prospective cohort studies.
Level 3 - non-randomized controlled study
Systematic review and meta-analysis of prospective observational cohort studies.
PubMed 27816065 · doi:10.1186/s12888-016-1075-3
What was done
A systematic review and meta-analysis of prospective cohort studies searched in PubMed, Embase, Web of Science, and CNKI through October 2014. A random-effects model was used to calculate pooled relative risk (RR) and 95% confidence intervals (CIs). Heterogeneity was evaluated using the I2 statistic and meta-regression, and publication bias was assessed via funnel plots, Egger's test, and trim-and-fill analysis.
What was found
The analysis included 34 cohort studies with 172,077 participants and an average follow-up of 60.4 months (ranging from 3.5 to 408 months). Insomnia was significantly associated with depression with a pooled RR of 2.27 (95% CI: 1.89-2.71). High heterogeneity was observed (I2 = 92.6%, P < 0.001). Funnel plot asymmetry and Egger's test indicated significant publication bias (P < 0.05), though correction with trim-and-fill did not alter the combined risk estimate.
Why it matters
This review aggregates longitudinal evidence confirming that insomnia symptoms consistently precede and more than double the subsequent risk of developing depression in non-depressed populations.
Limits
Heterogeneity across studies was extremely high (I2 = 92.6%), and follow-up duration varied widely from 3.5 months to 34 years. Significant publication bias was detected. Because this synthesizes observational cohort studies, unmeasured confounding and variations in how insomnia and depression were defined cannot be ruled out.
Cited by
- supports Sleep deprivation is associated with and can trigger depression.