Neural Mechanisms of Light Driven Analgesia

Inclusion Criteria for participants with cMSP and healthy controls (n=30) * Adults ≥18 years of age. * Individuals who do not have any plans for medication or treatment changes for the next 3 months. * Participants must be willing and able to undergo an MRI. * Participants must not be claustrophobic * Participants must be alert and oriented and able to provide informed consent. * Individuals must be able to speak and read English. Inclusion Criteria for participants with cMSP only (n=30) * To be eligible, participants must have a score of ≥7 on the Widespread pain index (WPI) and ≥5 on the symptom severity scale (SSS), or 4-6 on the WPI and ≥9 on the SSS in the 2016 Fibromyalgia Questionnaire. * Pain symptoms must have been present for 3 months or longer. * Pain must be present in 4 out of 5 body regions. * Individuals enrolled will have an average pain severity ≥4 on the 0-10 NRS over the month prior to enrollment to recruit individuals with moderate to severe chronic MSP. Inclusion Criteria for Participants with Congenital Stationary Night Blindness (n=2) -2 additional participants without chronic MSP will be recruited with diagnosed congenital stationary night blindness Exclusion Criteria: * Presence of retinal vision disorders or conditions resulting in vision impairment. * Patient-reported photosensitivity, photophobia, or aversion (as may occur in autoimmune diseases such as systematic lupus erythematosus). * Disorders including uveitis, cataracts, color-blindness, history of seizure disorder. * Plans for analgesic treatment plan changes in next 3 months (surgery, analgesic medication changes, injections, pain procedures, etc). * Prisoner Status. * Pregnancy. * Contraindications to MRI imaging. These include the presence of implanted/embedded ferromagnetic materials, implanted medical devices that are not MRI compatible, and claustrophobia.