Impact of sleep quality on health-related quality of life domains and the mediating effects of symptoms in people with multiple sclerosis

Many people living with multiple sclerosis (PwMS) experience poor sleep, which is associated with diminished overall health-related quality of life (HRQoL). We quantified associations between sleep quality and HRQoL domains and examined the extent to which other MS symptoms could account for these associations. In this cross-sectional survey of 1,717 Australians with MS, we used Assessment of Quality of Life (AQoL) 8D and Pittsburgh Sleep Quality Index (PSQI) to assess HRQoL and sleep quality, respectively. Total, direct, and indirect effects of sleep quality on HRQoL domains were determined using mediation regression analysis. Poor sleep quality was significantly associated with all domains of HRQoL, with strongest associations seen for mental health (β=-0.08) and pain (β=-0.11), and weaker associations for independent living (β=-0.05) and senses (β=-0.03). Poor sleep quality had the largest direct effect on mental health (60.8%), happiness (48.7%), and pain (49.7%). MS symptom clusters mostly contributing to indirect effects were "feelings of anxiety and depression" for psychosocial, and "pain and sensory symptoms" for physical HRQoL super dimensions. Improving sleep could lead to substantial improvements in all HRQoL domains and the improvement in HRQoL could be partially achieved through indirect improvements in sleep on MS symptoms.