Stroke and CPAP Outcome Study 3 Randomized Controlled Trial

Inclusion criteria include: 1. Age 18 years or older 2. Head CT or brain MRI demonstrating an acute ischemic infarction or intraparenchymal hemorrhage within past 30 days 3. Person providing consent (patient or legally authorized representative (LAR)) able to be consented in English or Spanish. Exclusion criteria include: 1. Unable to obtain informed consent from participant or LAR in English or Spanish 2. Incarcerated 3. Known pregnancy-determined by reviewing clinical data 4. Current mechanical ventilation, tracheostomy, or supplemental oxygen use \> 4L/min 5. Use of positive airway pressure within 14 days prior to stroke 6. History of pneumothorax, bullous emphysema or other serious co-morbid conditions which limit CPAP use 7. Stroke related to tumors, vascular malformations or subarachnoid hemorrhage 8. Active use of sedative drugs that can interfere with testing for obstructive sleep apnea (OSA) including any benzodiazepine, barbiturate, general anesthesia, or conscious sedation within the prior 48 hours of the planned portable sleep apnea study 9. Anticipated inpatient rehabilitation length of stay \< 5 nights 10. Co-morbid conditions that limit OSA testing or CPAP use in the judgement of the study team 11. Recent cranial or spinal surgery with known or possible CSF leak or pneumocephalus within past 3 months 12. Patients at significant risk of aspiration that could render the patient at risk of harm from use of CPAP, in the opinion of the site PI.