The association between objective measures of sleep and physical activity in individuals with multiple sclerosis

Sleep disturbances are common yet often overlooked in people with multiple sclerosis (pwMS), significantly impacting their quality of life. Although previous studies have explored the link between sleep and physical activity in pwMS, many lacked adequate control for key confounders such as depression, mobility impairments, and balance difficulties, which are independently associated with both sleep and activity. Additionally, reliance on self-reported data has limited the accuracy of findings. Understanding this relationship using objective measures is crucial, as poor sleep can exacerbate fatigue and further reduce quality of life. This study examined the association between objective sleep metrics and physical activity in pwMS while controlling for key confounders. A cross-sectional study was conducted with 50 pwMS (30 women, 20 men) aged 25-55 years, who wore an ActiGraph accelerometer for seven days to measure physical activity and sleep. Additional assessments included mobility (Timed Up and Go, Four Square Step Test, MS Walking Scale-12), fatigue (Modified Fatigue Impact Scale), and mental health (Hospital Anxiety and Depression Scale). Pearson's correlations and multiple linear regression models were used for analysis. Results showed that sleep efficiency was significantly associated with daily step counts and the maximum consecutive steps. Sleep measures accounted for 16-17 % of the variance in physical activity metrics, increasing to 30-35 % after adjusting for mobility and disability. These findings suggest a positive association between physical activity and sleep quality in pwMS, indicating that promoting physical activity may have potential benefits for sleep.