To evaluate sleepiness and central hypersomnia in multiple sclerosis (MS)–associated fatigue, we performed long-term polysomnography in patients with MS and healthy controls.
Patients with MS and healthy controls completed questionnaires on sleep, fatigue, sleepiness, and depression. They underwent nocturnal polysomnography, multiple sleep latency tests, and bed rest 24-hour polysomnography. Patients were divided into 3 groups (fatigue and sleepiness, fatigue and no sleepiness, neither fatigue nor sleepiness).
Among 44 patients with MS, 19 (43.2%) had fatigue and sleepiness, 15 (34%) had only fatigue, and 10 (22.7%) had neither fatigue nor sleepiness. Compared to 24 controls, patients with fatigue and sleepiness had higher REM sleep percentages (median [interquartile range] 20.5% [19.6–24.7] vs 18.1% [12.6–20.6]), lower arousal indexes (12.7 [7.5–17.0] vs 22.4 [14.3–34.4]), and shorter daytime mean sleep latencies (8.6 [6.3–14.3] vs 16.6 [12.6–19.5] min). Restless leg syndrome, periodic leg movements, and sleep apnea had similar frequencies between groups. Central hypersomnia was found in 10 (53%) patients with fatigue and sleepiness (narcolepsy type 2, n = 2), in 2 (13%) patients with fatigue only, and in 3 (30%) patients with neither fatigue nor sleepiness. Patients with central hypersomnia were younger and sleepier than those without hypersomnia, but had similar levels of fatigue, disability, depression, cognitive performance, and frequencies of the human leukocyte antigen DQB1*0602 genotype. The severity of fatigue increased with higher depression scores, higher sleepiness severity, and lower sleep efficacy.
Central hypersomnias are frequent in MS when fatigue and sleepiness are present. Screening them through polysomnography studies is recommended.