Are there sex differences in the influence of insomnia symptoms and sleep duration on the trajectory of neuromuscular strength decline?

Abstract Introduction A few longitudinal studies investigating the effect of sleep problems on the decline in neuromuscular strength (NMS) have produced conflicting results. Objective To examine sex differences in how insomnia symptoms (IS) and sleep duration (SD) affect the trajectory of NMS decline. Methods A longitudinal study with an eight-year follow-up period was conducted involving 6429 participants from the English Longitudinal Study of Ageing (ELSA) aged 50 or older. Participants with grip strength ≥27 kg for men and ≥16 kg for women were included. IS were investigated using a questionnaire adapted from Jenkins. SD was classified as short (≤6 h), ideal (>6 to <9 h), and long (≥9 h). Grip strength was the outcome. Generalised linear mixed models, stratified by sex and adjusted for sociodemographic, behavioural, clinical, and anthropometric variables, were used to estimate rates of NMS decline as a function of IS and SD. Results While an increase in IS was linked to a greater NMS decline rate in men (−0.02 kg per year; 95% CI: −0.04 to −0.01), women with SD ≥9 h experienced a higher rate of decline (−0.14 kg per year; 95% CI: −0.26 to −0.03). Conclusion Sex differences were observed in the influence of sleep problems on the rate of NMS decline. Insomnia has a greater effect on men, whereas longer SD affects women more.