FibromyalgiaNCT05569486
Elucidating the Central Mechanisms of Action for Green Light Therapy in Managing Chronic Pain
A study testing Green Light in people with Fibromyalgia, run by University of Arizona at 1 site in United States.
Trial summary
Investigators have previously shown that specific colors of light can alter nociception. Green light emitting diode exposure (GLED) provides long-lasting antinociception in rodents, through the visual system. No adverse effects were noted, and motor performance was not impaired. Read more about this study
- Who is it for?
- Ages 18 years and older
- Conditions the study is for
- Fibromyalgia
- What is being tested?
- Green Light
- Type of treatment
- Medical device
- Could I receive a placebo?
- Yes, some participants may receive a placebo
- How many people
- 70 participants
- Where
- 1 siteUnited States
- Study dates
- 1 Dec 2026to 30 Dec 2029
- Phase
- Interventional
- Are there results?
- Not yet: the study is under way
Key requirements
Who can take part, as listed by the sponsor. Only the study team can confirm whether you are eligible, so take this list to your doctor.
- Ages 18 years and older
- All sexes
- No healthy volunteers
- Adult, Older adult
Who may be able to join
- 18 years or older who can speak and understand English
- Meets the diagnostic criteria for fibromyalgia accroding to the 2016 revisions to the 2010/2011 fibromyalgia diagnostic criteria.
- Average numeric pain score of 5 out of 10 or greater over the 10 weeks prior to enrolling in the study, and failure of medical therapy to control their pain.
Who cannot join
- Serious mental illness defined as distortions of perception, delusions, hallucinations, and unusual behaviors resulting in loss of contact with reality. This will be assessed during the screening interview. Patients with psychiatric disorders will have their medical record reviewed prior to enrollment
- History of color blindness or uncorrected cataracts
- Subjects receiving remuneration for their medical condition.
- Genotype of low affinity binders for translocator protein, (TSPO), as patients with low affinity binding TSPO may not have adequate uptake for the radioactive tracer used for the PET scan.
Trial locations and contacts
1 site in 1 country. Contact the study team or a site near you to ask about taking part.
United States1 site
Banner University Medical Center Multispecialty Services Clinic
Tucson, Arizona, 85711
About this study
Official title: Elucidating the Central Mechanism(s) of Action for Green Light Therapy in Managing Chronic Pain
Investigators have previously shown that specific colors of light can alter nociception. Green light emitting diode exposure (GLED) provides long-lasting antinociception in rodents, through the visual system. No adverse effects were noted, and motor performance was not impaired. Investigator clinical trials have shown GLED is also effective in decreasing pain intensity of fibromyalgia patients and decreasing the number of headache-days per month in migraine patients. However, investigators do not yet understand the mechanisms by which GLED reduces pain.
Understanding the mechanisms of action of GLED will provide additional support for using light therapy as both a treatment and as a possible diagnostic tool. While investigators do not fully understand the mechanisms of action of GLED, investigators do know that it is centrally mediated.
To better elucidate the mechanism of action for GLED, investigators propose a single-blinded randomized placebo-controlled clinical trial to elucidate the central mechanism(s) of action that GLED therapy has in improving fibromyalgia pain, conducted by a team with a successful record of collaboration. Investigator's hypothesis is that GLED decreases neuroinflammation leading to modulation of the signaling in the ascending and descending pain pathways.
Read the detailed description
After a patient is consented, investigators will collect the baseline Fibromyalgia Impact Questionnaire survey (FIQ), thermal and mechanical pain detection and tolerance threshold, conditioned pain modulation (CPM), collect cerebrospinal fluid (CSF), and obtain positron emission tomography scan (PET scan) for microglia baseline activity. It is expected that the PET scan will take place on different day given the time needed and preparation for the completion of a PET scan. Investigators expect the baseline value collections to take 1-2 days to complete. Once all baseline values are obtained, the light therapy exposure will begin. The start of light exposure will be considered the start of Week 1. Investigators will follow up with the patient over the phone every 2 weeks +/- 1 week to ensure safety and compliance and to answer any questions the patient may have. Recruited patients will also have investigator's contact information to contact investigators with any urgent questions. At the end of Week 10, investigators will obtain the final values for the FIQ survey, thermal and mechanical pain detection and tolerance threshold, CPM, collect CSF, and obtain PET scan.
- Conditions
- Fibromyalgia
- Being tested
- Green Light
- Medical subject headings
- Fibromyalgia
What participants receive
What participants receive. In a randomised study each person is assigned to one group by chance.
Green LightDevice
This is a low-energy device. It produces almost no heat because it uses an LED source for light. The device does not store energy or electrical power that can be discharged later.
| Study group | Role | What they receive |
|---|---|---|
| Green light-emitting diode (GLED) | Experimental | Subjects randomized to this arm will be exposed to GLED 2 hours a day for 10 weeks Receives: Device: Green Light |
| White light-emitting diode (WLED) | Placebo comparator | Subjects randomized to this arm will be exposed to WLED 2 hours a day for 10 weeks Receives: Device: Green Light |
What is being measured
The primary outcome is the main question the study is designed to answer.
Decreased activation of glial cells.
By exposure to GLED investigators hypothesize that glial cells will be decreased, investigators will measure this by using positron emission tomography (PET) scan, scans will be conducted at baseline and the end of study
Measured: [Time Frame: 10 - 22 weeks, depending on study arm]
Secondary outcomes (4)
Decreasing Central Nervous System inflammation (CNS), Increasing Endorphins.
By exposure to GLED, investigators hypothesize that inflammation in the CSF will be decreased and increased endorphin levels, this will be demonstrated by measuring cerebrospinal fluid (CSF) cytokines at baseline and at the end of study.
Measured: [Time Frame: 10 - 22 weeks, depending on study arm]
Decreasing the activity of ascending pain pathway, and increasing the activity the descending pain pathway
Decreasing the activity of the ascending pain pathway shown by decreased pain scores from repeated noxious stimulation (temporal summation) as compared to baseline, increasing the activity of the descending pain pathway measured by increasing the pain threshold to noxious stimulation while patients submerge their hand in an ice water bath as compared to baseline.
Measured: [Time Frame: 10 - 22 weeks, depending on study arm]
Improvement in Fibromyalgia Impact Questionnaire score
These will be completed at baseline and at the end of study. A survey to evaluate the effects of Fibromyalgia. The scale ranges from 0-100. 0 means no impact. 100 means there is a severe negative impact secondary to fibromyalgia. The scale is subjective in nature.
Measured: [Time Frame: 10 - 22 weeks, depending on study arm]
Decreased objective and subjective pain scores to mechanical and thermal stimulation
Investigators will compare pain scores at baseline to end of study. The scale ranges from 0-100%. This is a reported value by the patient which is subjective in nature.
Measured: [Time Frame: 10 - 22 weeks, depending on study arm]
Timeline
From the start of the study to its completion; the mark is today. Estimated dates are the sponsor’s plan.
- First posted6 Oct 2022
- Study start1 Dec 2026 (estimated)
- Primary completion30 Dec 2029 (estimated)
- Study completion30 Dec 2029 (estimated)
Resources
- Official record on ClinicalTrials.govThe registry entry this page is built from, with its full change history.
- Publications (6)Papers the sponsor has linked to this study.
- Other trials for FibromyalgiaStudies of the same condition, open and under way.
- More trials run by University of ArizonaThe sponsor's other registered studies.
- What the trial phases meanHow a treatment moves from first tests in people to approval.
More details
For doctors and researchers: how the study is designed, who runs it, and its registry IDs.
Study design
- Study type
- Interventional
- Phase
- Phase N/A
- Primary purpose
- Treatment
- Allocation
- Randomised
- Intervention model
- Parallel groups
- Masking
- None (open label)
- Enrolment
- 70 participants (estimated)
Sponsor and investigators
- Lead sponsor
- University of Arizona
- Sponsor type
- University, hospital or other
- Collaborators
- Banner Alzheimer's Institute
- Responsible party
- Principal investigator, Mohab Ibrahim, PhD MD, University of Arizona
- Investigators
- Mohab M Ibrahim, PhD., MD, Principal investigator, University of Arizona
IDs, dates and publications
- ClinicalTrials.gov ID
- NCT05569486
- Sponsor's protocol ID
- 00000333
- Status last verified
- Mar 2026
- First submitted
- 3 Oct 2022
- Last updated
- 3 Apr 2026
- Results posted
- No
- Data monitoring committee
- No
- FDA-regulated drug
- No
- FDA-regulated device
- Yes
- Individual data sharing
- No
Publications
Burckhardt CS, Clark SR, Bennett RM. The fibromyalgia impact questionnaire: development and validation. J Rheumatol. 1991 May;18(5):728-33.
PubMed 1865419Potvin S, Marchand S. Pain facilitation and pain inhibition during conditioned pain modulation in fibromyalgia and in healthy controls. Pain. 2016 Aug;157(8):1704-1710. doi: 10.1097/j.pain.0000000000000573.
PubMed 27045524Overstreet DS, Michl AN, Penn TM, Rumble DD, Aroke EN, Sims AM, King AL, Hasan FN, Quinn TL, Long DL, Sorge RE, Goodin BR. Temporal summation of mechanical pain prospectively predicts movement-evoked pain severity in adults with chronic low back pain. BMC Musculoskelet Disord. 2021 May 10;22(1):429. doi: 10.1186/s12891-021-04306-5.
PubMed 33971876Mackey IG, Dixon EA, Johnson K, Kong JT. Dynamic Quantitative Sensory Testing to Characterize Central Pain Processing. J Vis Exp. 2017 Feb 16;(120):54452. doi: 10.3791/54452.
PubMed 28287532Yarnitsky D, Bouhassira D, Drewes AM, Fillingim RB, Granot M, Hansson P, Landau R, Marchand S, Matre D, Nilsen KB, Stubhaug A, Treede RD, Wilder-Smith OH. Recommendations on practice of conditioned pain modulation (CPM) testing. Eur J Pain. 2015 Jul;19(6):805-6. doi: 10.1002/ejp.605. Epub 2014 Oct 20.
PubMed 25330039Yarnitsky D, Granot M, Nahman-Averbuch H, Khamaisi M, Granovsky Y. Conditioned pain modulation predicts duloxetine efficacy in painful diabetic neuropathy. Pain. 2012 Jun;153(6):1193-1198. doi: 10.1016/j.pain.2012.02.021. Epub 2012 Apr 3.
PubMed 22480803
Study at a glance
From the registry record, last updated by the sponsor on 3 Apr 2026. Recruitment status is as the sponsor reported it: confirm with the study team.
- Official title
- Elucidating the Central Mechanism(s) of Action for Green Light Therapy in Managing Chronic Pain
- ClinicalTrials.gov ID
- NCT05569486
- Acronym / sponsor ID
- 00000333
- Conditions
- Fibromyalgia
- Study type
- Interventional
- Recruitment status
- Not yet recruiting
- Enrolment
- 70 participants (estimated)
- Lead sponsor
- University of ArizonaUniversity, hospital or other
- Collaborators
- Banner Alzheimer's Institute
- Study start
- 1 Dec 2026 (estimated)
- Primary completion
- 30 Dec 2029 (estimated)
- Study completion
- 30 Dec 2029 (estimated)
- First posted
- 6 Oct 2022 (actual)
- Results
- Not posted in the source record
Clinical summary
The research question as the sponsor registered it. This describes what the study plans to test, not what it found.
Investigators have previously shown that specific colors of light can alter nociception. Green light emitting diode exposure (GLED) provides long-lasting antinociception in rodents, through the visual system. No adverse effects were noted, and motor performance was not impaired. Investigator clinical trials have shown GLED is also effective in decreasing pain intensity of fibromyalgia patients and decreasing the number of headache-days per month in migraine patients. However, investigators do not yet understand the mechanisms by which GLED reduces pain.
Understanding the mechanisms of action of GLED will provide additional support for using light therapy as both a treatment and as a possible diagnostic tool. While investigators do not fully understand the mechanisms of action of GLED, investigators do know that it is centrally mediated.
To better elucidate the mechanism of action for GLED, investigators propose a single-blinded randomized placebo-controlled clinical trial to elucidate the central mechanism(s) of action that GLED therapy has in improving fibromyalgia pain, conducted by a team with a successful record of collaboration. Investigator's hypothesis is that GLED decreases neuroinflammation leading to modulation of the signaling in the ascending and descending pain pathways.
Detailed description
After a patient is consented, investigators will collect the baseline Fibromyalgia Impact Questionnaire survey (FIQ), thermal and mechanical pain detection and tolerance threshold, conditioned pain modulation (CPM), collect cerebrospinal fluid (CSF), and obtain positron emission tomography scan (PET scan) for microglia baseline activity. It is expected that the PET scan will take place on different day given the time needed and preparation for the completion of a PET scan. Investigators expect the baseline value collections to take 1-2 days to complete. Once all baseline values are obtained, the light therapy exposure will begin. The start of light exposure will be considered the start of Week 1. Investigators will follow up with the patient over the phone every 2 weeks +/- 1 week to ensure safety and compliance and to answer any questions the patient may have. Recruited patients will also have investigator's contact information to contact investigators with any urgent questions. At the end of Week 10, investigators will obtain the final values for the FIQ survey, thermal and mechanical pain detection and tolerance threshold, CPM, collect CSF, and obtain PET scan.
Study design
- Primary purpose
- Treatment
- Allocation
- Randomised
- Intervention model
- Parallel groups
- Masking
- None (open label)
- Number of arms
- 2
| Arm | Type | Receives |
|---|---|---|
| Green light-emitting diode (GLED) | Experimental | Device: Green LightSubjects randomized to this arm will be exposed to GLED 2 hours a day for 10 weeks |
| White light-emitting diode (WLED) | Placebo comparator | Device: Green LightSubjects randomized to this arm will be exposed to WLED 2 hours a day for 10 weeks |
Who may qualify
- Ages
- 18 years and older
- Sex
- All
- Healthy volunteers
- Not accepted
- Age groups
- Adult, Older adult
Key inclusion criteria (3 listed)
- 18 years or older who can speak and understand English
- Meets the diagnostic criteria for fibromyalgia accroding to the 2016 revisions to the 2010/2011 fibromyalgia diagnostic criteria.
- Average numeric pain score of 5 out of 10 or greater over the 10 weeks prior to enrolling in the study, and failure of medical therapy to control their pain.
Key exclusion criteria (4 listed)
- Serious mental illness defined as distortions of perception, delusions, hallucinations, and unusual behaviors resulting in loss of contact with reality. This will be assessed during the screening interview. Patients with psychiatric disorders will have their medical record reviewed prior to enrollment
- History of color blindness or uncorrected cataracts
- Subjects receiving remuneration for their medical condition.
- Genotype of low affinity binders for translocator protein, (TSPO), as patients with low affinity binding TSPO may not have adequate uptake for the radioactive tracer used for the PET scan.
Eligibility is decided by the study team after screening; this overview does not establish that a patient qualifies. Full inclusion and exclusion criteria.
Interventions
| Intervention | Type | Arms |
|---|---|---|
| Green LightThis is a low-energy device. It produces almost no heat because it uses an LED source for light. The device does not store energy or electrical power that can be discharged later. | Device | Green light-emitting diode (GLED), White light-emitting diode (WLED) |
Primary outcome
Decreased activation of glial cells.
Time frame: [Time Frame: 10 - 22 weeks, depending on study arm]
By exposure to GLED investigators hypothesize that glial cells will be decreased, investigators will measure this by using positron emission tomography (PET) scan, scans will be conducted at baseline and the end of study
4 secondary outcomes
Decreasing Central Nervous System inflammation (CNS), Increasing Endorphins.
Time frame: [Time Frame: 10 - 22 weeks, depending on study arm]
Decreasing the activity of ascending pain pathway, and increasing the activity the descending pain pathway
Time frame: [Time Frame: 10 - 22 weeks, depending on study arm]
Improvement in Fibromyalgia Impact Questionnaire score
Time frame: [Time Frame: 10 - 22 weeks, depending on study arm]
Decreased objective and subjective pain scores to mechanical and thermal stimulation
Time frame: [Time Frame: 10 - 22 weeks, depending on study arm]
Results and safety
This study is still under way. Results are not available in the source record yet.
Research links
- Official record on ClinicalTrials.govLast updated by the sponsor 3 Apr 2026.
- Background: PubMed 1865419Burckhardt CS, Clark SR, Bennett RM. The fibromyalgia impact questionnaire: development and validation. J Rheumatol. 1991 May;18(5):728-33.
- Background: PubMed 27045524Potvin S, Marchand S. Pain facilitation and pain inhibition during conditioned pain modulation in fibromyalgia and in healthy controls. Pain. 2016 Aug;157(8):1704-1710. doi: 10.1097/j.pain.0000000000000573.
- Background: PubMed 33971876Overstreet DS, Michl AN, Penn TM, Rumble DD, Aroke EN, Sims AM, King AL, Hasan FN, Quinn TL, Long DL, Sorge RE, Goodin BR. Temporal summation of mechanical pain prospectively predicts movement-evoked pain severity in adults with chronic low back pain. BMC Musculoskelet Disord. 2021 May 10;22(1):429. doi: 10.1186/s12891-021-04306-5.
- Background: PubMed 28287532Mackey IG, Dixon EA, Johnson K, Kong JT. Dynamic Quantitative Sensory Testing to Characterize Central Pain Processing. J Vis Exp. 2017 Feb 16;(120):54452. doi: 10.3791/54452.
- Background: PubMed 25330039Yarnitsky D, Bouhassira D, Drewes AM, Fillingim RB, Granot M, Hansson P, Landau R, Marchand S, Matre D, Nilsen KB, Stubhaug A, Treede RD, Wilder-Smith OH. Recommendations on practice of conditioned pain modulation (CPM) testing. Eur J Pain. 2015 Jul;19(6):805-6. doi: 10.1002/ejp.605. Epub 2014 Oct 20.
- Background: PubMed 22480803Yarnitsky D, Granot M, Nahman-Averbuch H, Khamaisi M, Granovsky Y. Conditioned pain modulation predicts duloxetine efficacy in painful diabetic neuropathy. Pain. 2012 Jun;153(6):1193-1198. doi: 10.1016/j.pain.2012.02.021. Epub 2012 Apr 3.
- Individual participant dataSharing planned: No
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Referral and contact
AzTrials does not enrol participants or take referrals. Contact the study team or a site listed below; they decide who can take part.
Mohab M Ibrahim, PhD., MD principal investigator
University of Arizona
1 site in 1 country: see every site and its status.
Questions about this trial
What is this clinical trial studying?
A study testing Green Light in people with Fibromyalgia, run by University of Arizona at 1 site in United States.
The full registered description is in the About this study section and the official record.
Who may be eligible to take part?
The sponsor lists 3 inclusion and 4 exclusion criteria. Eligibility is decided by the study team after screening, so read the full criteria and contact a listed site.
Is this clinical trial currently recruiting?
The record says: opening soon, as of the sponsor's last update on 3 Apr 2026. Status can change between updates, so confirm with the study contact before making plans.
Where is the study taking place?
The record lists 1 site in United States. Whether a site is taking part right now should be confirmed with that site. See every site.
What are the possible benefits and risks?
They depend on the study and the treatment, and no study can promise a benefit. Some participants in this study may receive a placebo. The study team explains the known risks during informed consent, before anyone joins; the record itself does not list them.
Are results available for this study?
This study is still under way. Results are not available in the source record yet.
How can a doctor refer a patient or contact the research team?
Contact Mohab M Ibrahim, PhD., MD (520-871-7246, mibrahim@anesth.arizona.edu), or a site near the patient. AzTrials does not enrol participants or take referrals.
What does the primary outcome measure?
Decreased activation of glial cells. (time frame: [Time Frame: 10 - 22 weeks, depending on study arm]). It is what the study was designed to measure, not a finding.
Where can I read the original study information?
On the ClinicalTrials.gov record for NCT05569486, which also lists 6 linked publications.
Does a listing mean the treatment is approved or proven to work?
No. A listing means the study is registered. It does not show that the treatment is safe, works, or is approved by a regulator.
How often is this information updated?
AzTrials copies changed records from ClinicalTrials.gov every night and reloads the whole registry every week. The sponsor last updated this record on 3 Apr 2026.