An interventional study of S-Cone Stimulating Chromatic Light and Equal-Energy White Light in Fibromyalgia and Musculoskeletal Pain, sponsored by University of North Carolina, Chapel Hill. Recruiting at 1 site in United States. Open to participants aged 18 Years and older. Per ClinicalTrials.gov, last updated 2026-11-02.
Sponsored by University of North Carolina, Chapel Hill · Not applicable, Interventional, and Treatment
This pilot randomized, double-blind, crossover clinical trial will evaluate the feasibility and preliminary efficacy of chromatic (colored) light exposure for reducing pain severity and pain sensitivity in adults with fibromyalgia or chronic widespread pain and fatigue. Participants will complete daily symptom surveys throughout the study and undergo patient-reported outcome assessments and quantitative sensory testing at multiple timepoints.
Participants will be randomized to receive either S-cone stimulating chromatic light or equal-energy white light for 2 hours daily over a 7-day treatment period. Following a 1-week washout, participants will cross over to the alternate condition. Outcomes will examine feasibility, changes in pain severity, pain interference, and measures of pain sensitivity. Total study duration is approximately 35 days.
This pilot, randomized, double-blind, crossover clinical trial is designed to evaluate the feasibility of administering a chromatic light intervention and to explore its effects on pain severity and pain sensitivity in adults with fibromyalgia or chronic widespread pain and fatigue.
Following informed consent and enrollment, baseline assessments will be performed which will include demographic and health questionnaires, validated patient-reported outcome measures, and quantitative sensory testing (QST), including assessments of conditioned pain modulation, temporal summation, and pressure pain threshold.
Participants will then be randomly assigned to one of two treatment sequences:
S-cone stimulating chromatic light during Treatment Period 1 followed by equal-energy white light during Treatment Period 2.
Equal-energy white light during Treatment Period 1 followed by S-cone stimulating chromatic light during Treatment Period 2.
The study utilizes commercially available "TUO" programmable light bulbs that deliver pre-programmed light spectra. Participants will receive study equipment, including five programmed light bulbs, portable lamps, and an illuminometer to verify that the intervention light intensity is at least twice the ambient room illumination. Participants will use the assigned light condition for 2 hours daily, ideally between 5:00 a.m. and 10:00 a.m., for 7 consecutive days while engaging in normal daily activities.
At the end of the first treatment period, participants will return for repeat patient-reported outcome assessments and quantitative sensory testing. Participants will then complete a 1-week washout period during which no light intervention is administered, although daily symptom surveys will continue. Following washout, participants will cross over to the alternate light condition and complete a second 7-day treatment period identical to the first.
After completion of the second treatment period, participants will undergo final intervention assessments, return study equipment, and enter a 1-week follow-up period with continued daily symptom monitoring. At the final study visit, participants will complete follow-up questionnaires and optional quantitative sensory testing.
The primary objective is to determine the feasibility and acceptability of delivering chromatic light therapy for 2 hours daily across two treatment periods. Secondary objectives include evaluating whether chromatic light exposure reduces chronic pain severity and pain sensitivity to a greater extent than an equal-energy white light control condition. Approximately 40 participants will be enrolled, and total participation time will be approximately 35 days. Risks associated with the intervention are expected to be minimal and primarily include potential light sensitivity or discomfort and standard risks related to data confidentiality.
1,243 studies on the registry are indexed under Fibromyalgia; 256 are open to participants now.
This study's planned enrollment of 40 is below the median of 60 across 937 interventional studies indexed under Fibromyalgia.
Browse Fibromyalgia studies →University of North Carolina, Chapel Hill is the lead sponsor of 1,372 studies on the registry; 133 are open to participants now.
Of its 161 completed or terminated interventional studies of FDA-regulated products, 139 (86%) have results posted.
Counted across the registry records on this site, refreshed daily.
Go through the criteria one by one — yes, no or not sure — and take the list to your doctor or the study team. Kept in this browser only.
Exclusion Criteria:
Underlined terms in the criteria open these too. Explained by clinicaltrials.gg, not part of the registry record. The study team decides who can take part.
Before you join, the study team explains what taking part involves — its purpose, what happens, the risks and possible benefits — and answers your questions, so you can decide freely. Consent is usually recorded on a form (the informed consent form, ICF) signed by you or, where the law allows, by someone legally authorised to decide for you.
You can keep asking questions during the study, you are told of new information that matters, and you can choose to leave at any time.
Informed consent
Before you join, the study team explains what taking part involves — its purpose, what happens, the risks and possible benefits — and answers your questions, so you can decide freely. Consent is usually recorded on a form (the informed consent form, ICF) signed by you or, where the law allows, by someone legally authorised to decide for you.
You can keep asking questions during the study, you are told of new information that matters, and you can choose to leave at any time.
Explained by clinicaltrials.gg, not part of the registry record. The study team decides who can take part.
Participants randomized to this sequence will receive S-cone stimulating chromatic light during the first treatment period, followed by equal-energy white (flickering along the L/M axis) light during the second treatment period. Each treatment period consists of 2 hours of daily light exposure for 7 consecutive days, ideally between 5:00 a.m. and 10:00 a.m., delivered using programmed "TUO" light bulbs. The two treatment periods are separated by a 1-week washout period. Participants complete daily symptom surveys, patient-reported outcome measures, and quantitative sensory testing throughout the study.
Device: S-Cone Stimulating Chromatic Light · Device: Equal-Energy White Light
Participants randomized to this sequence will receive equal-energy white light (flickering along the L/M axis) during the first treatment period, followed by S-cone stimulating chromatic light during the second treatment period. Each treatment period consists of 2 hours of daily light exposure for 7 consecutive days, ideally between 5:00 a.m. and 10:00 a.m., delivered using programmed "TUO" light bulbs. The two treatment periods are separated by a 1-week washout period. Participants complete daily symptom surveys, patient-reported outcome measures, and quantitative sensory testing throughout the study.
Device: S-Cone Stimulating Chromatic Light · Device: Equal-Energy White Light
Participants receive exposure to S-cone stimulating chromatic light delivered via programmed TUO light bulbs. Light is administered for 2 hours daily for 7 consecutive days, ideally between 5:00 a.m. and 10:00 a.m.. Participants use the light in their home environment while engaging in normal daily activities. Light intensity is maintained at a minimum of twice the ambient room illumination using an illuminometer provided by the study. This intervention is designed to selectively stimulate short-wavelength-sensitive (S-cone) photoreceptors.
Participants receive exposure to a light that appears equal-energy white that flickers along the L/M axis delivered via programmed TUO light bulbs. Light is administered for 2 hours daily for 7 consecutive days, ideally between 5:00 a.m. and 10:00 a.m. Participants use the light in their home environment while engaging in normal daily activities. Light intensity is maintained at a minimum of twice the ambient room illumination using an illuminometer provided by the study. This intervention serves as the control condition for comparison with the S-cone stimulating chromatic light intervention.
Percentage of participants completing follow-up visits after each intervention period
Feasibility will be assessed by percentage of participants completing follow-up visits after each intervention period.
Time frame: Throughout study participation (35 days)
Percentage of daily flash surveys completed during the two 7-day stimulation periods
Feasibility will be assessed by percentage of daily flash surveys completed during the two 7-day stimulation periods (14 eligible survey time points).
Time frame: Throughout the two 7-day stimulation periods (14 eligible survey timepoints during active treatment period)
Percentage of prescribed light stimulation sessions completed based on participant self-report
Feasibility will be assessed by percentage of prescribed light stimulation sessions completed based on participant self-report.
Time frame: Throughout the two 7-day stimulation periods (14 eligible survey timepoints during active treatment period)
Pain Intensity
Pain severity will be measured using an 11-point Numeric Rating Scale (NRS), where 0 represents no pain and 10 represents the worst pain imaginable. Mean pain scores following S-cone stimulating light and equal-energy white light conditions will be compared.
Time frame: Baseline, post-treatment period 1 (Day 14), post-treatment period 2 (Day 28), and follow-up (Day 35)
Pressure Pain Threshold
Pressure pain threshold will be assessed using a pressure algometer applied to the trapezius muscle. Outcomes will be recorded in kilograms of force per square centimeter (kgf/cm\^2). Higher values indicate greater pain tolerance and reduced pain sensitivity.
Time frame: Baseline, post-treatment period 1 (Day 14), and post-treatment period 2 (Day 28).
Temporal Summation
Temporal summation will be assessed using a 256 millinewton (mN) pinprick stimulator. Pain intensity ratings following a single stimulus and a train of 10 repetitive stimuli will be used to quantify central pain facilitation. Lower temporal summation values indicate reduced pain sensitivity.
Time frame: Baseline, post-treatment period 1 (Day 14), and post-treatment period 2 (Day 28).
Conditioned Pain Modulation
Conditioned pain modulation will be calculated as the difference in pressure pain threshold measured before and after a conditioning cold-water stimulus. Greater increases in pressure pain threshold following conditioning indicate more effective endogenous pain inhibition.
Time frame: Baseline, post-treatment period 1 (Day 14), and post-treatment period 2 (Day 28).
Plan to share: No
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Start is estimated for Nov 2026; primary completion for Jan 2028, 13 months later.
Of 436 non-industry interventional studies with no phase under Fibromyalgia, half reached primary completion within 16 months of starting (the median), counting those still running; a quarter within 6 and three quarters within 31. This study's planned 13 months is below that.
Counting every sponsor, half of 449 studies reached it within 15 months; a quarter within 6 and three quarters within 31.
Start moved once since we started tracking on Sep 25, 2026: Sep 2026 → Nov 2026, on Nov 2, 2026.
Earlier changes are on the record history on ClinicalTrials.gov ↗
How these figures are worked out, and which studies are left out of them.
From the registry record's own update history. This site started tracking changes on Sep 25, 2026; for anything earlier, see the record history on ClinicalTrials.gov ↗
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