We achieved a unique and timely recording of cerebral activity in a 70 year old woman immediately pre- and post-stroke, while studying the effect of acute cerebral infarction on sleep-electroencephalogram (EEG) patterns. Normal patterns, except for increased wakefulness, were recorded during two pre-infarct polysomnograms. Immediately following cerebral infarction increased delta activity was recorded from the infarcted hemisphere only. Initially, REM sleep could not be recorded from either side; however, on the third post infarct day REM sleep returned. Background EEG levels from both hemispheres became progressively slower, flatter and simpler. In addition, sleep spindles and the distinctive saw-tooth wave forms of sleep almost disappeared. At one year post-stroke sleep-EEG rhythm recordings from both hemispheres became more similar except for persisting delta activity from the left hemisphere. Unexpected deterioration of sleep-EEG pattern recordings from the undamaged hemisphere taken during the patient's clinical recovery remains unexplained. Serial sleep recording may facilitate the study of brain recovery, activity and reorganization following stroke.