• Nocturnal myoclonus has been identified as a cause of disturbed sleep and excessive daytime fatigue. To our knowledge, no therapy has heretofore been available to adequately control this problem. We identified this problem clinically in two patients; in one, the phenomenon was observed with a polygraphic sleep recording. Small doses of clonazepam, 1 mg, before retiring were found to specifically control the myoclonus and allow sleep patterns to return to normal.