Daytime sleepiness might increase the risk of ALS: a 2-sample Mendelian randomization study

Abstract

Background: Observational studies have indicated that there is a high prevalence of habitual sleep disturbances in amyotrophic lateral sclerosis (ALS). However, the actual relationship between these symptoms and ALS remains unclear.

Methods: We used 2-sample Mendelian randomization to determine whether the sleep disturbances associated with ALS are also related to the risk of ALS. The summary statistics we used were from recent, large genome-wide association studies on daytime sleepiness and other night sleep traits (n = 85,670-452,071) and ALS (n = 20,806 cases, n = 59,804 controls). The inverse variance-weighted (IVW) method was used as the main method for assessing causality.

Results: Daytime sleepiness might increase the risk of ALS (IVW odds ratio = 2.45, 95% confidence interval: 1.15-5.21; P = 0.020). ALS was not associated with sleep efficiency, number of sleep episodes or sleep duration.

Conclusions: Our results provide novel evidence that daytime sleepiness increases the risk of ALS and points out the importance of daytime sleepiness that often goes unnoticed in ALS.

Keywords: Amyotrophic lateral sclerosis; Daytime sleepiness; Mendelian randomization; Sleep disturbances.