Inclusion Criteria- greater than 18 years of age
- admitted to an inpatient rehabilitation unit at the University of Washington
- head CT or brain MRI demonstrating an ischemic or hemorrhagic stroke
- enrolled in another research study
Exclusion Criteria- stroke was a subarachnoid hemorrhage or due to a secondary cause (vascular malformation, vasculitis, brain tumor, head trauma, or predisposition to bleeding)
- history of CPAP use, advanced chronic lung disease requiring supplemental oxygen, heart failure (NYHA class III or IV)
- require a nasogastric feeding tube.