Daytime sleepiness is known to be related to stroke, but whether daytime sleepiness is a risk factor for stroke remains unclear. We conducted a two-sample Mendelian randomization study to assess the relationship between daytime sleepiness and stroke, ischemic stroke (IS) and IS subtypes.
Thirty-six single-nucleotide polymorphisms (SNPs) associated with daytime sleepiness were selected as instrumental variables, which were identified from a recent genome-wide association study(N = 452,071). Summary statistics of the SNPs on stroke, IS and IS subtypes were derived from the MEGASTROKE consortium with 40,585 stroke cases and 406,111 controls.
We found that daytime sleepiness was associated with large artery stroke (OR, 6.75; 95%CI, 1.49-30.57; p = 0.013), but not with all stroke (OR, 1.29; 95%CI, 0.81-2.05; p = 0.282), all ischemic stroke(OR, 1.46; 95%CI, 0.90-2.39; p = 0.136), cardioembolic stroke(OR, 1.0; 95%CI, 0.39-2.64; p = 0.984), or small artery stroke(OR, 1.52; 95%CI, 0.46-5.05; p = 0.485).
Our findings indicated that daytime sleepiness is causally associated with an increased risk of large artery stroke. Further studies are necessary to verify our results and explain the physiological mechanisms.

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