BACKGROUND AND PURPOSE Sleep apnea is very common after stroke and is associated with poor outcome. Supine sleep is known to exacerbate apneas in the general sleep apnea population. We therefore investigated the pattern of sleep positions in the acute stroke period. METHODS Inpatients with acute ischemic stroke underwent full polysomnography that included continuous monitoring of sleep positions. Sleep apnea severity was measured using the apnea-hypopnea index (AHI). Stroke severity was measured by the NIH Stroke Scale (NIHSS) at the time of study enrollment by certified study personnel. Percent total sleep time spent in the supine position was calculated and compared by stroke severity based on a median split of NIHSS using a Wilcoxon rank-sum test. RESULTS Of the 30 patients, the median age was 67. The median AHI was 23 (IQR: 6, 47). Twenty-two patients (73%) had sleep apnea with an AHI >/=5. The vast majority of sleep time among the stroke cases was spent supine, with a median percent sleep time spent supine of 100 (IQR: 62, 100). The majority (63%) of subjects spent no time asleep in any of the nonsupine positions (prone, left, right). Median percent sleep time supine was 100 (IQR: 100, 100) in those with a higher NIHSS and 63 (IQR: 51, 100) in those with a lower NIHSS (P<0.01). CONCLUSIONS Given the high prevalence of supine sleep identified, research into positional therapy for stroke patients with sleep apnea seems warranted.