The underdiagnosis of sleep disorders in patients with multiple sclerosis

To report at a population level the prevalence of restless legs syndrome, insomnia, and the risk of obstructive sleep apnea in multiple sclerosis patients. Sleep patterns and associations with fatigue and daytime sleepiness were identified.

A cross-sectional study was performed using a written survey that was mailed to 11,400 individuals from the Northern California Chapter of the National Multiple Sclerosis (MS) Society Database who self-identified as having MS. The survey included individual questions relating to demographics as well as several standard validated questionnaires related to primary sleep disorders, sleepiness, fatigue severity, and sleep patterns.

Among the 11,400 surveys mailed out, 2,810 (24.6%) were returned. Of these, 2,375 (84.5%) met the inclusion criteria. Among the completed surveys, 898 (37.8%) screened positive for obstructive sleep apnea, 746 (31.6%) for moderate to severe insomnia, and 866 (36.8%) for restless legs syndrome. In contrast, only 4%, 11%, and 12% of the cohort reported being diagnosed by a health care provider with obstructive sleep apnea, insomnia, and restless legs syndrome, respectively. Excessive daytime sleepiness was noted in 30% of respondents based on the Epworth Sleepiness Scale. More than 60% of the respondents reported an abnormal level of fatigue based on the Fatigue Severity Scale. Both abnormal fatigue and sleepiness scores were associated with screening positive for obstructive sleep apnea, insomnia, and restless legs syndrome.

A significant percentage of MS subjects in our sample screened positive for one or more sleep disorders. The vast majority of these sleep disorders were undiagnosed. Greater attention to sleep problems in this population is warranted, especially in view of fatigue being the most common and disabling symptom of MS.