The Simplify Project

The investigators will perform sleep studies using nocturnal EEG measurements and oximetry 1) while the participants are still in the hospital but have reached relative clinical stability (≥48 h after admission, not in ICU and pHv ≥7.36) and 2) two months after hospital discharge at the participant's home. Sleep studies will be performed from 5:00 pm to 8 am. EEG measurements will be performed using a portable monitor (Prodigy Sleep System, Cerebra, Winnipeg, Canada). Sleep assessment will be performed offline. The ORP will be continuously quantified and ORP-derived indices will be calculated. Nocturnal oximetry will be used for detecting sleep desaturation episodes. Comorbidities (e.g., obesity, diagnosed lung or heart disease, Charlson comorbidity index) and exacerbations/hospitalization in the previous year will be identified. In 21 participants, the investigators will perform one additional sleep study with the participants breathing with high-flow nasal cannula therapy (HFNC) to investigate the acute impact (i.e., during one night) of HFNC on reducing sleep abnormalities. HFNC will be set from 25 - 60 L/min based on participant's tolerance and the inspired fraction of oxygen will be titrated to maintain patient SpO2 similar to the levels during standard oxygen therapy.