Inclusion Criteria:  Aged ≥18 years; Fluent in English; Able to provide informed consent.  Exclusion Criteria:  Contraindication to esophageal pressure monitoring, including a sensitive gag reflex (determined by a positive response to the screening question "do you sometimes or often gag while brushing your teeth?"), dysphagia, nasal obstruction, and/or esophageal disorder likely to impact placement of the balloon; Pregnancy or planned pregnancy during the study (self-reported); History of allergic reactions to medical adhesives; Known allergy to lidocaine; Known seizure disorder; Severe medical condition (controlled or uncontrolled) impacting breathing including neuromuscular disease, chronic obstructive pulmonary disease, respiratory failure or insufficiency, or requirement for oxygen therapy; Chronic cardiopulmonary or renal disease, including a history of irregular heart rhythms or dyspnea; At risk for excessive bleeding including use of anticoagulants; An employee, or spouse of an employee, of a company that designs, sells, or manufactures sleep related products (including Philips); An employee, or spouse of an employee, of Pulmonary & Critical Care Associates of Baltimore.