Exploring genetic association of insomnia with allergic disease and asthma: a bidirectional Mendelian randomization study

Background: Insomnia is highly prevalent among patients with allergic disease and asthma; however, few studies have investigated their causal relationship. We aim to explore the causal association between insomnia and allergic disease/asthma by performing bidirectional Mendelian randomization (MR) study. Methods: Instrumental variables were constructed using single nucleotide polymorphisms (SNPs). Summary statistics for insomnia, allergic disease, and asthma were obtained from four large-scale genome-wide association studies (GWAS) of European ancestry. The pleiotropy analysis was applied by using the MR-Egger intercept test and the MR pleiotropy residual sum and outlier (MR-PRESSO) test. MR analyses were conducted by using inverse variance weighted (IVW), weighted median, and MR-Egger method. Results: Based on the multiplicative random effects IVW method, the MR analysis showed that genetically predicted insomnia was causally associated with an increased risk of allergic disease [odds ratio (OR) = 1.054, 95% confidence interval (CI) = 1.031–1.078, P = 3.817 × 10–06], asthma (OR = 1.043, 95% CI = 1.010–1.077, P = 9.811 × 10–03), moderate-severe asthma (OR = 1.168, 95% CI = 1.069–1.277, P = 6.234 × 10–04), and adult-onset asthma (OR = 1.086, 95% CI = 1.037–1.138, P = 4.922 × 10–04). In bidirectional analyses, we did not find evidence supporting the reverse causality relations. Conclusions: Our MR study suggested that genetically predicted insomnia was the risk factor for allergic disease and asthma. Improving sleep quality could be one of the cornerstones in the prevention of allergic disease and asthma.