FIGURE 3 | Summary of the Mendelian randomization (MR) analysis for insomnia on major depression (MDD). (A) MR effect size of each instrumental variable (IV), MR-Egger, and inverse variance weighted (IVW). (B) Scatter plot of causal effects of insomnia on MDD. We use vertical and horizontal black lines to show 95% CI of the estimated effectofIVsonMDD(x-axis)and thatoninsomnia(y-axis), respectively. WeusethebluelinetoshowtheIVWrandom-effectsmodel. ThepotentialSNP outlier (rs11693221) is highlighted in green. (C) Funnel plot of the causal effect of insomnia on MDD. Each point represents the estimated causal effect of each IV. The verticaldark blue line represents the causal effect estimate obtained using the MR-Egger method; the light blue linerepresents the causal effect estimate obtained using the IVW method. The potential outlier (rs11693221) is highlighted in