The wife of a 78-year-old man had noticed that he would occasionally wake from sleep, sit up, gesture whilst mumbling a few confused words, collapse back then ‘return to sleep’. The frequency of the episodes was increasing and for the past week had occurred almost every night. On each occasion he was pale, cold, and unresponsive for several minutes after returning to sleep. On waking he would be distressed by short periods of retrograde amnesia lasting up to 4 hours from before he went to bed. He was otherwise completely unaware of these episodes. Neurological and cardiovascular examinations...

The wife of a 78-year-old man had noticed that he would occasionally wake from sleep, sit up, gesture whilst mumbling a few confused words, collapse back then ‘return to sleep’. The frequency of the episodes was increasing and for the past week had occurred almost every night. On each occasion he was pale, cold, and unresponsive for several minutes after returning to sleep. On waking he would be distressed by short periods of retrograde amnesia lasting up to 4 hours from before he went to bed. He was otherwise completely unaware of these episodes. Neurological and cardiovascular examinations were normal in the clinic.