Nocturnal sleep-related ventilatory alterations may occur in dis-proportion to the severity of the neuromuscular disorder. Diaphragm paralysis occurring with a neuromuscular disorder is an overlooked complication. Failure to thrive, daytime tiredness, and incapacitating fatigue may be the result of a correctable sleep-related abnormality, not the result of relentless progression of a neuromuscular condition. Polysomnographic evaluation is recommended for patients who have neuromuscular disorder who develop symptoms and signs of sleep-wake abnormality or nocturnal respiratory failure. Application of noninvasive positive airway ventilation and, in some cases, administration of supple-mental oxygen may improve quality of life and prolong survival of patients who have neuromuscular disorder.