Sex differences in insomnia: a meta-analysis.
Level 3 - non-randomized controlled study
Systematic review and meta-analysis of observational epidemiologic studies
PubMed 16453985 · doi:10.1093/sleep/29.1.85
What was done
A systematic review and meta-analysis of published epidemiological studies was conducted to evaluate sex differences in insomnia risk in the general population. Comprehensive database searches and snowball sampling identified 31 papers, with 29 studies (1,265,015 participants: 718,828 females and 546,187 males) providing data for the overall meta-analysis across nine subgroup analyses.
What was found
Females showed a significantly higher risk of insomnia than males, with a pooled risk ratio of 1.41 (95% CI 1.28–1.55). The female excess was larger in higher-quality, larger studies and increased progressively with age, reaching greater prominence in the elderly. Variation in diagnostic criteria, frequency, or duration definitions did not alter the female predisposition, and while the female excess was observed across different regions, it was relatively lower in East Asia.
Why it matters
This review establishes a consistent female predominance in insomnia risk across diverse global populations and shows that the sex disparity widens across the lifespan.
Limits
The source literature consists entirely of observational epidemiological surveys with varying diagnostic definitions. Mechanisms driving the observed sex difference were not evaluated in the data.