DAYTIME SLEEP IN MYOTONIC-DYSTROPHY IS NOT CAUSED BY SLEEP-APNEA

Daytime sleepiness is common in myotonic dystrophy and might be attrib uted to disturbed nocturnal breathing. Seventeen out of 22 patients co mplained of excessive daytime sleepiness, resembling ''idiopathic hype rsomnolence'' Sleep apnoea might have contributed to daytime sleepines s in only three of 17 patients. Treatment with the central stimulant m ethylphenidate 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.