Obstructive 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.

Inclusion Criteria:

• Cognitively normal (Telephone Interview for Cognitive Status (TiCS) ≥29))
• Moderate - severe OSA
• Currently on therapy for OSA and has received treatment for OSA for at least 3 months.
• Sustained compliance with continuous positive airway pressure (CPAP), which means using the machine at least 4 hours per night for five nights a week.
• Epworth Sleepiness Score (ESS) greater than or equal to 8 or excess daytime sleepiness as defined by the Functional Outcome Sleep Questionnaire or clinical complaint.

Exclusion Criteria:

• Documented diagnosis of chronic insomnia, or sleep onset insomnia based on Insomnia Severity Index (ISI)
• Documented diagnosis of circadian rhythm disorder
• Any current use of supplemental oxygen
• Other sleep-related breathing disorders (central sleep apnea, etc.) based on American Academy of Sleep Medicine (AASM) criteria
• Current shift work involving night shift (regular work between 12am and 6am or night shift) within the past 6 months
• Anticipated scheduled bariatric surgery within the next 3 months
• Chronic regular (> 2 nights per week) use of any sedative, stimulant, neuroleptic drugs, or other medications limiting validity of cognitive tests. This includes regular use of alcohol or marijuana for sleep. Melatonin is ok.
• Diagnosis of uncontrolled psychiatric disease in the last six months, and/or history of schizophrenia or bipolar disorder. Controlled conditions will include major depressive disorder, panic disorder, schizoaffective disorder, generalized anxiety disorder, Obsessive-compulsive disorder (OCD), substance use disorders, and alcohol abuse/dependence. Personality disorders and neurodevelopmental disorders (e.g. autism, ADHD) are allowed if cognition is within normal limits.
• Taking methylphenidate for ADHD.
• Presence of other critical comorbid conditions that would lead to inability to complete the study protocol (including follow-up for 2 years), or that would affect cognition (e.g. clinically relevant endocrine or hematological conditions).
• Chronic regular (> 2 nights per week) use of stimulant if unable to complete a washout prior to MRI.
• Does not have a regular sleeping environment (i.e., sleeps in a different setting > 2 nights per week).
• Currently pregnant or planning to become pregnant.
• Prior diagnosis of a Central nervous system (CNS) disease, such as multiple sclerosis, stroke, Parkinson's disease, Alzheimer's disease, epilepsy, a loss of consciousness > 24 hours, or traumatic brain injury as identified by the Cumulative Illness Rating Scale for Geriatrics (CIRS). Participants who are diagnosed with Mild cognitive impairment (MCI) or Alzheimer's disease based on neuropsychological testing will be excluded. Delirium in the last 12 months.
• Near-miss or prior automobile accident "due to sleepiness" within the past 12 months.
• Employed as a commercial driver during the study (for example, bus drivers, train engineers, airplane pilots) or construction worker.
• Past intolerance or hypersensitivity to tPBM.
• Significant skin conditions (i.e., hemangioma, scleroderma, psoriasis, rash, open wound or tattoo) on the subject's scalp that are found in the area of the procedure sites.
• Any use of light-activated drugs (photodynamic therapy) within 14 days prior to study enrollment.
• Any type of implants in the head, whose functioning might be affected by tPBM (e.g., stent, clipped aneurysm, embolized arteriovenous malformation (AVM), implantable shunt - Hakim valve).
• Failure to meet standard MRI safety requirements (e.g., claustrophobia, non-removable piercings, implanted medical devices, other non-removable metals) as determined by the MRI Safety Checklist.

The de-identified participant data from the final research dataset will be shared upon reasonable request beginning 9 to 36 months after publication or as required by a condition of awards or supporting agreements, provided the requesting investigator executes a data use agreement with NYU Langone Health. This instance of data sharing will also require separate IRB review as well as review from NYU Langone's Data Sharing Strategy Board (DSSB). Requests should be directed to: Naomi.Gaggi@nyulangone.org. The protocol and statistical analysis plan will be posted on Clinicaltrials.gov only as required by federal regulation or supporting awards and agreements.

Beginning 9 months and ending 36 months following article publication or as required by a condition of awards and agreements supporting the research.

The investigator who proposed to use the data will be granted access upon reasonable request. Requests should be directed to Naomi.Gaggi@nyulangone.org. To gain access, data requestors will need to sign a data access agreement. This instance of data sharing will also require separate IRB review as well as review from NYU Langone's DSSB.