RecruitingDevice studyObstructive Sleep Apnea Therapeutic Intervention for REsiDual SleepinessObstructive sleep apnea (OSA) is a sleep disorder that is commonly treated using positive airway pressure, yet 50% of patients still experience residual sleepiness after successful therapy. A potential neuromodulation strategy that can decrease residual sleepiness is transcranial photobiomodulation (tPBM). tPBM is a neuromodulatory treatment that uses red and/or near infrared light to penetrate the cortex and can alter both cerebral metabolism and blood flow. However, this potential has never been explored before directly in sleep disordered individuals. This project aims to explore the effect of tPBM on sleepiness and understand the potential neural mechanism of tPBM in OSA. The short-term goal of this project is to collect pilot data, which is the first of its kind, and suggest tPBM as a potential modulator of sleepiness in OSA.