Nonobvious connections between napping and stroke: a systematic review and meta-analysis

We present a meta-analysis and systematic review of research on the relationships between various aspects of naps and stroke risk. Two searches were conducted: a bibliographic search in four electronic databases for published articles that considered associations between the duration of napping and stroke risk versus a reference group (who did not nap) (n = 13) from inception up to July 15, 2024. The second search analyzed different features of napping (e.g., frequency, mild or severe napping, planned or unplanned, etc.) and stroke risk (n = 7). We found that the studies were very methodologically heterogeneous. Several publications reported more than one effect size. These differences allowed us to build models that describe the associations between napping and stroke. We used a funnel plot to estimate publication bias and employed a model of random effects for the analysis. The duration of naps was significantly associated with stroke risk; naps of 1-30 min had an odds ratio (OR) of 1.27, whereas naps >90 min had an OR of 1.79. Mutated forest plots were used to visualize the overall effects. We describe the pathomechanisms associated with an increased risk of hypertension and diabetes, mild inflammation, and other risk factors for stroke.