We report 12 patients with nonepileptic seizures (NESs) documented with video-electroencephalographic monitoring during apparent sleep. There were 7 females and 5 males, ages 11 to 67 years (mean, 33 yr). In all patients there was a well-organized posterior alpha rhythm present immediately before onset of clinical changes despite the appearance of sleep. Patients later "confirmed" that these attacks occurred during sleep. Features of these episodes were typical of NESs and none were associated with ictal or postictal electroencephalographic changes other than muscle and movement artifact. Provocative testing with suggestion confirmed the nonepileptic nature of these episodes in 9 patients. Three patients had epileptiform discharges during prolonged interictal recordings and 1 had a documented complex partial seizure. Our findings indicate that reports of seizures during sleep are not uncommon among patients with NESs.