[Disturbances of wakefulness, sleep and respiratory function in Steinert's disease]

36 night sleep recordings were carried out on 15 patients suffering from myotonia dystrophica. 9 of these patients complained of diurnal hypersomnia. 10 patients had a disturbance of night sleep with a reduction of REM sleep sometimes associated with interruption of the recording with an increase in the light stages of sleep or alternatively with an increase of REM sleep with a reduction in the latency period of the first paradoxical sleep or with narcoleptic elements. 13 patients had abnormally early abolition of chin EMG activity, almost on falling asleep. 11 cases had pathological apnoeic episodes during sleep and in 9 of the 10 patients who underwent respiratory function studies there was a restrictive airways defect. In addition 9 had frank hypoxia without hypercapnia and 4 a right to left shunt. 3 clinically unaffected patients but with affected relatives were also investigated, 2 were found to have sleep disturbances 1 of which was associated with early abolition of tone.