A preliminary investigation of sleep quality in functional neurological disorders: poor sleep appears common, and is associated with functional impairment

Purpose Functional neurological disorders (FND) are disabling conditions for which there are few empirically-supported treatments. Disturbed sleep appears to be part of the FND context; however, the clinical importance of sleep disturbance (extent, characteristics and impact) remains largely unknown. We described sleep quality in two samples, and investigated the relationship between sleep and FND-related functional impairment. Methods We included a sample recruited online via patient charities (N = 205) and a consecutive clinical sample (N = 20). Participants completed validated measures of sleep quality and sleep characteristics (e.g. total sleep time, sleep efficiency), mood, and FND-related functional impairment. Results Poor sleep was common in both samples (89% in the clinical range), which was characterised by low sleep efficiency (M = 65.40%) and low total sleep time (M = 6.05 h). In regression analysis, sleep quality was negatively associated with FND-related functional impairment, accounting for 16% of the variance and remaining significant after the introduction of mood variables. Conclusions These preliminary analyses suggest that subjective sleep disturbance (low efficiency, short sleep) is common in FND. Sleep quality was negatively associated with the functional impairment attributed to FND, independent of depression. Therefore, sleep disturbance may be a clinically important feature of FND.