Medications for Opioid Use Disorder Photosensitive Retinal Ganglion Cell Function, Sleep, and Circadian Rhythms: Implications for Treatment

Inclusion Criteria: 1. Adults (18+) 2. prescribed one of three medications for opioid use disorder (methadone, XR-NTX, buprenorphine) or healthy control 3. stable on MOUD (no dose change) for the past month 4. positive on urine drug screen (UDS) for buprenorphine or methadone if prescribed those medications Exclusion Criteria: 1. eye disease reported by history or noted on exam including disease of the anterior and posterior segment of the eye, cataracts, retinopathy, glaucoma, cataracts, amblyopia, scotoma, color or night blindness, corneal pathologies, macular degeneration, or retinitis pigmentosa; 2. acutely suicidal, manic, intoxicated, or otherwise not stable enough to provide informed consent 3. self-reported use of illicit opioids, stimulants (prescribed or illicit), or benzodiazepines/sedative/hypnotics in the past month 4. alcohol or cannabis use disorder measured as severe on The Diagnostic and Statistical Manual of Mental Disorders, Fifth Edition (DSM-5) Checklist 5. positive on UDS for illicit opioids (e.g., morphine, oxycodone, fentanyl),stimulants, benzodiazepines/sedative/hypnotics 6. shift workers who work outside normal 7 a.m. to 6 p.m. hours, according to the National Institute of Occupational Safety and Health (NIOSH) 7. persons diagnosed with narcolepsy