Myasthenia Gravis (MG) is an autoimmune neuromuscular disorder that is associated with disturbed night time sleep and/or daytime manifestations of sleep disturbance such as fatigue. 49 yo woman, underwent Polysomnography (PSG) adaptation. After 2 days a baseline PSG was performed to evaluate the sleep pattern and Periodic Leg Movement (PLM) index. Subsequent to one week of baseline PSG, the patient performed an acute physical exercise (Maximum Effort Test - MET) in the morning and subsequent PSG at night. We demonstrate a reduction in the PLM index. Recognition of the benefits of exercise may modify plan of treatment and follow-up of MG patients.