This is a study (1994) that looked at the causes of sleepiness in patients with myotonic dystrophy. They concluded that these sleep issues are not caused by sleep apnea. A number of the patients were able to get some relief with Ritalin. Ritalin has a low amount of cardiac side effects. However, this drug may have some cardiac side effects so clear it with your doctor cardiologist before use
Daytime Sleepiness is not caused by Sleep Apnea
Daytime sleep in myotonic dystrophy is not caused by sleep apnoea.
Source
Department of Neurology, University Hospital Rotterdam-Dijkzigt, The Netherlands.
Abstract
Daytime sleepiness is common in myotonic dystrophy and might be attributed to disturbed nocturnal breathing. Seventeen out of 22 patients complained of excessive daytime sleepiness, resembling “idiopathic hypersomnolence”. Sleep apnoea might have contributed to daytime sleepiness in only three of 17 patients. Treatment with the central stimulant methylphenidate produced sustained benefit in seven out of 11 patients tested. Daytime sleepiness in myotonic dystrophy is usually caused by dysfunction of central sleep regulation and not by disturbed nocturnal breathing.