Sleep Quality in Neuromyelitis Optica Spectrum Disorder: A Systematic Review.

Background: This review summarizes the literature on sleep quality in neuromyelitis optica spectrum disorder (NMOSD) and discusses these findings in the context of current knowledge of sleep physiology. Methods: A literature search was performed using Ovid MEDLINE, Embase, and Scopus from inception to September 3, 2020. All included studies reported at least 1 measure of sleep quality in individuals with NMOSD. Pittsburgh Sleep Quality Index (PSQI) scores of individuals from 4 studies were compared with those from a data set of controls. Results: Thirteen studies (1041 individuals with NMOSD) were included in the review. Disturbed sleep was demonstrated across subjective metrics based on patient surveys and objective metrics such as polysomnography. An estimated 70% of individuals with NMOSD can be classified as poor sleepers. Standardized mean difference between PSQI scores of 183 individuals with NMOSD and those of 9284 controls was 0.72 (95% CI, 0.57-0.86; Conclusions: Sleep disturbances are a major contributor to NMOSD disease burden and may arise from the disruption of sleep circuitry, in addition to physical and psychological complications. Multiple processes involved in sleep regulation may be affected, such as, but not limited to, neural circadian circuit disruption, direct effects of inflammation, aminergic projecting system abnormalities, glymphatic system impairment, and development of sleep disorders such as restless legs syndrome/sleep apnea. A better understanding of these mechanisms is necessary for developing effective therapies for NMOSD-associated sleep disturbances.