The causal relationship between sleep disturbances and the risk of frailty: a two-sample Mendelian randomization study

Objective Adequate sleep is closely related to people's health. However, with increasing age, the quality of sleep worsens. At the same time, among elderly individuals, frailty is also a disturbing factor, which makes elderly individuals more vulnerable to negative factors. To explore the relationship between the two, we conducted this study. Methods In this paper, independent genetic variations related to insomnia, sleep duration and daytime sleepiness were selected as IVs, and related genetic tools were used to search published genome-wide association studies for a two-sample Mendelian randomization (TSMR) analysis. The inverse-variance weighted (IVW) method was used as the main Mendelian randomization analysis method. Cochran's Q test was used to test heterogeneity, MR‒Egger was used to test horizontal pleiotropy, and the MR-PRESSO test was used to remove outliers. Results According to our research, insomnia (OR = 1.10, 95% CI 1.03–1.17, P = 2.59e−97), long sleep duration (OR = 0.66, 95% CI 0.37–1.17, P = 0.02), short sleep duration (OR = 1.30, 95% CI 1.22–1.38, P = 2.23e−17) and daytime sleepiness (OR = 1.49, 95% CI 1.25–1.77, P = 0.96e−4) had a bidirectional causal relationship with frailty. Conclusions Our research showed that there is a causal relationship between sleep disturbances and frailty. This result was obtained by a TSMR analysis, which involves the use of genetic variation as an IV to determine causal relationships between exposure and outcome. Future TSMR studies should include a larger sample for analysis.