Two cases of myotonic dystrophy with excessive daytime somnolence are described. All-night polysomnographic studies were performed revealing high number of central sleep apnea which triggered micro-arousals and awakenings leading to decrease of sleep efficiency as well as of stage 3, 4 and REM. Obstructive and mixed apneas were found in the normal range. Hypoxia was not present in both recordings. Central sleep apneas and its secondary excessive daytime sleepiness may indicate early signs of the central nervous system impairment related to myotonic dystrophy, as a multi-organ disease.