Sleep pattern and breathing in humans are altered following cerebrovascular accidents involving the brainstem. Sleep apnea is a well-established complication of stroke involving the brainstem. On the other hand, the effect of cerebral stroke on sleep and breathing has not been well defined. The diffuse cerebral symptoms such as cognitive deficits, depression or fatigue, after hemispheric stroke mimic those present in patients with sleep apnea. To define the breathing pattern in patients with stroke involving cerebral hemispheres without brainstem lesion and without the prior history of sleep-disordered breathing, we studied 10 patients within 1 year of their stroke. The data collected during polysomnography from the stroke patients were compared with a group of subjects matched for age, body mass index, presence of hypertension, and smoking history without stroke. Patients with stroke had an abnormal sleep architecture with significantly lower slow wave sleep and rapid eye movement (REM) sleep when compared with controls. Sleep was fragmented because of the presence of increased respiratory disturbances. Stroke patients had a respiratory disturbance index of 52 +/- 10 events per hour when compared with 3 +/- 1 in controls (p < .05). Majorities of respiratory events were obstructive apneas and were associated with arterial oxygen desaturations and arousals. The pathogenic mechanism of sleep-disordered breathing in patients with hemispheric stroke seems to be related to the physiological effect of sleep on already compromised upper airway muscle control. Patients with stroke and diffuse cerebral symptoms should be investigated for the possibility of sleep-disordered breathing.