Daytime sleepiness in the general population is associated with reduced quality of life (QOL), lower job performance and increased risk of accidents. It can also be a symptom of obstructive sleep apnea (OSA), a serious condition and a contraindication for certain medications. Previous reports on sleep disturbances in small MS samples suggest both daytime sleepiness and OSA to be common.
To establish the prevalence of self-reported sleep disturbances and daytime sleepiness in a large MS population and assess symptoms and factors associated with the most severe cases.
We analyzed responses to sleep-specific questions administered to NARCOMS Registry participants in spring 2009 in conjunction with a routine semi-annual survey that assesses disability status using Patient Determined Disease Steps (PDDS) and Performance Scales (PS), and QOL using the Short-Form 12 (SF12). Sleep-specific questions included the Epworth Sleepiness Scale (ESS), diagnosed sleep disorders including OSA and insomnia, and the Berlin questionnaire. Group comparisons were based on the total score on the ESS (range 0-32), where a score ≥9 indicates clinically relevant daytime sleepiness and scores ≥16 are considered severe.
The 7713 registry participants who completed the sleep-related section of the survey were predominantly white (91.9%) and women (77%). On average (SD) they were 55.4 (10.5) years old and had a disease duration of 16.7 (9.8) years. Their median (IQR) PDDS score was 4 [1, 6] and PS fatigue score 3 [2, 4]. 4309 (55.9%) reported snoring and 2906 (37.7%) periodic limb movements. Almost a third (31.5%) scored ≥9 on the ESS, including 449 (5.8%) with a score ≥16. Despite similar age and disease duration, the ≥16 group had higher PDDS disability (5 [3,7] vs. 4 [1,6]) and PS fatigue score (4 [3,4] vs. 2 [1,3]) than those scoring below 9, and scored considerably lower in both physical (30.6 vs. 37.8) and mental (39.6 vs. 48.1) domains of the SF12. They were also more likely to report snoring (60.9% vs. 52.6%), periodic limb movements (53.7% vs. 33%) and falling asleep while driving (30.8% vs. 5.2%). Despite the reported symptoms, only 24.6% of all responders had a medical diagnosis of either insomnia (17.6%) or OSA (7.0%) with a third of those diagnosed currently not treated.
Sleep disturbances and daytime sleepiness are common in MS and potentially under-treated. Severe cases are associated with higher levels of disability and lower QOL in both physical and mental domains.