[Neuromuscular disease and sleep disturbance]

In neuromuscular diseases, respiratory disorder is related to sleep disorder. In Duchenne muscular dystrophy, respiratory muscle disorder progresses and induces alveolar hypoventilation. Hypoxemia and hypercapnia develop, requiring appropriate management. Hypoxemia first appears during sleep, initially occurring during the REM period, and it progresses and becomes persistent. Not only a decrease in the respiratory muscle strength but also upper respiratory tract obstruction due to soft palatal hypertrophy or a decrease in the muscle tension during sleep causes noctural ventilatory impairment. Hypoxemia is severe at dawn, and reduces the quality of life, inducing poor arousal in the morning, headache, and decreased appetite. Sleep fragmentation causes hypersomnia during the day. When ventilation is maintained using a respirator, almost all problems are overcome. In myotonic dystrophy type 1, there are respiratory control and sleep disorders due to central nerve abnormalities in addition to respiratory muscle lesions. Even in the stage of mild respiratory muscle lesions, hypoxemia during sleep sometimes appears. Hypersomnia during the day is also an important symptom. Hypersomnia does not disappear even after the correction of hypoxemia using a respirator.