Further observations on sleep abnormalities in Kleine-Levin syndrome: abnormal breathing pattern during sleep.

In two adolescent and two adult patients with Kleine-Levin syndrome, polygraphic sleep recording performed during somnolent and non-somnolent periods revealed various forms of abnormal breathing patterns during sleep. These included periodic breathing and hypopnoeic episodes associated with brief arousals and, in one adult patient, a full blown sleep apnoea syndrome. It is suggested that abnormal breathing in sleep in this syndrome may result from central hypoexcitability.