Meta-Analysis of 1.3 Million Finds Chronic Insomnia Tied to 26% Higher Stroke Risk

The review pooled nine stroke studies and five hospitalization studies, performing meta-analyses on six and three cohorts respectively. Insomnia was defined by persistent difficulty initiating or maintaining sleep with daytime impairment; most cohorts relied on self-report or diagnostic codes rather than polysomnography. Pooled hazard ratios showed consistent elevation after adjustment for age and sex, though residual confounding by sleep apnea, medications, and socioeconomic status remained unmeasured in several datasets.

Mechanistic pathways cited include sustained sympathetic activation, elevated cortisol, reduced heart-rate variability, and accelerated atherosclerosis. These overlap with established stroke and dementia risk factors yet the review could not isolate insomnia as an independent driver. Prior large cohorts such as the Nurses’ Health Study and UK Biobank have reported similar gradients, suggesting the signal is reproducible but still associative.

Next steps require prospective trials that treat insomnia with CBT-I or orexin antagonists and track adjudicated vascular and cognitive endpoints over five-plus years. Without randomization, clinicians cannot yet infer that insomnia treatment alters hard outcomes beyond symptom relief and quality of life.