Cognitive flexibility remains an unproven link between insomnia and depression
Studies generally found no clear associations along this proposed pathway, and none directly tested whether cognitive flexibility explains the insomnia–depression relationship.
Based on the published abstract. The full paper may contain additional methods, results and limitations.
The 30-second takeaway
The review found little support for reduced cognitive flexibility as the process connecting insomnia with later depression. Most associations were null, including consistently null longitudinal findings for insomnia and cognitive flexibility. Because no study directly tested the complete pathway, these findings leave the proposed mechanism unproven rather than showing that it is impossible.
The abstract supplies no pooled effect sizes, participant totals or follow-up lengths. Indirect associations cannot establish the proposed causal pathway, and null findings do not demonstrate that meaningful effects are impossible.
Separate links were examined
The authors examined 35 studies of insomnia and cognitive flexibility, plus 11 studies asking whether cognitive flexibility predicts later depression. These groups addressed separate links; none formally tested the complete mediation model.
Positive findings had limited scope
Some associations appeared only in older participants or benzodiazepine users, or disappeared after adjustment. Associations with later depression were more evident among people without depression at baseline, so they should not be generalized to all participants.
The original publication
Evaluating reduced cognitive flexibility as a link between Insomnia and future depression: A systematic review.
Crawford CA, Minor KS, Cyders MA et al.
Sleep Med · 2025
- PubMed ID
- 41014697
- Record checked
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