Sleep disorders in childhood-onset myotonic dystrophy type 1.

Slowness, fatigue, and learning difficulties are common in young patients with myotonic dystrophy type 1. These features may indicate poor sleep quality. The aim of this study was to search for sleep disorders in this population. This prospective study used questionnaires, genetic testing, night-time polysomnography and multiple sleep latency tests to evaluate objective daytime sleepiness. Twenty-one patients were included. Mean age was 15.0+/-3.0. Age of onset of myotonic disorders was after birth and before 10 years old. Age of diagnosis was 12.0+/-2.9. Fatigue was reported by 76% of patients, while somnolence was present in 52%. Sleep was disturbed by numerous microarousals (mean 16.6+/-7.3/h of sleep) caused by abnormal respiratory events (6/21 patients) and/or periodic limb movements (8/21 patients). In young patients with DM1, complaints of fatigue and/or somnolence should lead to a polysomnography to look for sleep apnea syndrome and/or periodic limb movement, which were present in two-thirds of our population.