Chronic PainNCT05295225
Green Light Exposure in Healthy Volunteers Exposure in Normal Human Volunteers
A study testing Green Light Emitting Diode and White Light Emitting Diode in people with Chronic Pain, run by University of Arizona at 1 site in United States.
Trial summary
This research project is intended to understand the mechanisms of action for the pain-relieving properties of visual green light exposure. The investigators have shown previously that greenlight exposure decreased acute and chronic pain in both animals and humans. Read more about this study
- Who is it for?
- Ages 18 to 50 yearsHealthy volunteers can take part
- Conditions the study is for
- Chronic Pain
- What is being tested?
- Green Light Emitting Diode and White Light Emitting Diode
- Type of treatment
- Medical device
- Could I receive a placebo?
- Yes, some participants may receive a placebo
- How many people
- 30 participants
- Where
- 1 siteUnited States
- Study dates
- 14 Jun 2022to 31 Dec 2026
- 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 to 50 years
- All sexes
- Healthy volunteers accepted
- Adult
Who may be able to join
- 18-50 years healthy men or women
- Able to speak and understand English
- No history of Chronic pain
- No known neuropathies in areas that testing will take place, (forearms, muscle at the base of thumb on the palm of the hand and upper back/shoulder area.
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.
- Colorblindness or uncorrected cataracts.
- Tissue damage in areas that testing will take place, (forearms, muscle at the base of the thumb on the palm of the hand, and upper back/should area.
Trial locations and contacts
1 site in 1 country.
United States1 site
Banner University Medical Center Tucson
Tucson, Arizona, 85724
About this study
Official title: Investigating the Analgesic Effects of Green Light Exposure in Normal Human Volunteers
This research project is intended to understand the mechanisms of action for the pain-relieving properties of visual green light exposure.
The investigators have shown previously that greenlight exposure decreased acute and chronic pain in both animals and humans. However, the investigators do not yet understand how green light exposure is capable of such function.
Read the detailed description
Pain is a biological function. There are several pain centers in the brain that modulate the intensity of the pain signal perceived by the brain. Part of the modulations takes place through two separate pathways. The first pathway mediates pain signals and is known as the ascending facilitator pain pathway. The main function of this pathway is to relay the pain signal to the brain to be processed.
The second pathway is known as the descending inhibitory pain pathway. The main function of this pathway is to inhibit the pain signal mediated by the first pathway.
Normal humans typically have a balance between the activities of the ascending and descending pain pathways.
The investigator animal studies suggest that green light therapy exhibits its pain-relieving effects through altering the balance between the ascending and descending pain pathway in a manner to result in an overall reduction or normalization in pain perception.
To test this hypothesis, the investigators propose recruiting 30 healthy human volunteers. The participants will be equally randomized into either green light (treatment) or white light (control) exposure groups. The investigators will initially test the activities of the ascending and descending pathways using thermal and mechanical stimulations. The investigators will also test brain wave activities using a non-invasive EEG device. After establishing the baseline activities of the pain pathways and brain waves, the volunteers will be exposed to the green light or white light at low intensity (4-100 lux) for two hours in our laboratory. After two hours of light exposure, the investigators will again test the activities of the pain pathways using thermal and mechanical stimulation and measure the brain wave EEG activities.
- Conditions
- Chronic Pain
- Being tested
- Green Light Emitting Diode, White Light Emitting Diode
- Medical subject headings
- Chronic Pain
What participants receive
What participants receive. In a randomised study each person is assigned to one group by chance.
Green Light Emitting DiodeDevice
Also called GLED
GLED exposure for two hours
White Light Emitting DiodeDevice
Also called WLED
WLED exposure for two hours
| Study group | Role | What they receive |
|---|---|---|
| Green Light Exposure | Active comparator | Subjects will complete thermal and mechanical pain threshold detection tests and Electroencephalography (EEG). After completion, subjects will be exposed to a green light-emitting diode for two hours. After exposure, thermal and mechanical pain threshold assessments and Electroencephalography (EEG) will be conducted. Receives: Device: Green Light Emitting Diode |
| White Light Exposure | Placebo comparator | Subjects will complete thermal and mechanical pain threshold detection tests and Electroencephalography (EEG). After completion, subjects will be exposed to a white light-emitting diode for two hours. After exposure, thermal and mechanical pain threshold assessments and Electroencephalography (EEG) will be conducted. Receives: Device: White Light Emitting Diode |
What is being measured
The primary outcome is the main question the study is designed to answer.
Ascending Pain Pathway
Changes in activity of the ascending pain pathway
Measured: Two hours
Descending Pain Pathway
Changes in activity of the descending pain pathway
Measured: Two hours
Secondary outcomes (5)
Delta Brain Activities
Changes in the baseline of Delta waves of EEG
Measured: Two hours
Theta Brain Activities
Changes in the baseline of Theta waves of EEG
Measured: Two hours
Alpha Brain Activities
Changes in the baseline of Alpha waves of EEG
Measured: Two hours
Sigma Brain Activities
Changes in the baseline of Sigma waves of EEG
Measured: Two hours
Beta Brain Activities
Changes in the baseline of Beta waves of EEG
Measured: Two hours
Timeline
From the start of the study to its completion; the mark is today. Estimated dates are the sponsor’s plan.
- First posted25 Mar 2022
- Study start14 Jun 2022
- Primary completion31 Dec 2026 (estimated)
- Study completion31 Dec 2026 (estimated)
Resources
- Official record on ClinicalTrials.govThe registry entry this page is built from, with its full change history.
- Publications (2)Papers the sponsor has linked to this study.
- Other trials for Chronic PainStudies 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
- Basic science
- Allocation
- Randomised
- Intervention model
- Parallel groups
- Masking
- None (open label)
- Enrolment
- 30 participants (estimated)
Sponsor and investigators
- Lead sponsor
- University of Arizona
- Sponsor type
- University, hospital or other
- Responsible party
- Principal investigator, Mohab Ibrahim, PhD MD, University of Arizona
- Investigators
- Mohab Ibrahim, PhD, MD., Principal investigator, University of Arizona
IDs, dates and publications
- ClinicalTrials.gov ID
- NCT05295225
- Sponsor's protocol ID
- 00000370
- Status last verified
- Dec 2025
- First submitted
- 22 Feb 2022
- Last updated
- 5 Jan 2026
- Results posted
- No
- Data monitoring committee
- No
- FDA-regulated drug
- No
- FDA-regulated device
- No
- Individual data sharing
- No
Publications
Ibrahim MM, Patwardhan A, Gilbraith KB, Moutal A, Yang X, Chew LA, Largent-Milnes T, Malan TP, Vanderah TW, Porreca F, Khanna R. Long-lasting antinociceptive effects of green light in acute and chronic pain in rats. Pain. 2017 Feb;158(2):347-360. doi: 10.1097/j.pain.0000000000000767.
PubMed 28092651Ismail KA, Curfman V, Park J, Louis EM, Korah H, Washington SM, Ibrahim MM, Martin LF. Optimizing Photoneuromodulation Techniques to Evaluate the Role of Green Light-Emitting Diodes in Pain Management. J Vis Exp. 2025 Mar 28;(217). doi: 10.3791/67821.
PubMed 40227987
Study at a glance
From the registry record, last updated by the sponsor on 5 Jan 2026. Recruitment status is as the sponsor reported it: confirm with the study team.
- Official title
- Investigating the Analgesic Effects of Green Light Exposure in Normal Human Volunteers
- ClinicalTrials.gov ID
- NCT05295225
- Acronym / sponsor ID
- 00000370
- Conditions
- Chronic Pain
- Study type
- Interventional
- Recruitment status
- Active, not recruiting
- Enrolment
- 30 participants (estimated)
- Lead sponsor
- University of ArizonaUniversity, hospital or other
- Study start
- 14 Jun 2022 (actual)
- Primary completion
- 31 Dec 2026 (estimated)
- Study completion
- 31 Dec 2026 (estimated)
- First posted
- 25 Mar 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.
This research project is intended to understand the mechanisms of action for the pain-relieving properties of visual green light exposure.
The investigators have shown previously that greenlight exposure decreased acute and chronic pain in both animals and humans. However, the investigators do not yet understand how green light exposure is capable of such function.
Detailed description
Pain is a biological function. There are several pain centers in the brain that modulate the intensity of the pain signal perceived by the brain. Part of the modulations takes place through two separate pathways. The first pathway mediates pain signals and is known as the ascending facilitator pain pathway. The main function of this pathway is to relay the pain signal to the brain to be processed.
The second pathway is known as the descending inhibitory pain pathway. The main function of this pathway is to inhibit the pain signal mediated by the first pathway.
Normal humans typically have a balance between the activities of the ascending and descending pain pathways.
The investigator animal studies suggest that green light therapy exhibits its pain-relieving effects through altering the balance between the ascending and descending pain pathway in a manner to result in an overall reduction or normalization in pain perception.
To test this hypothesis, the investigators propose recruiting 30 healthy human volunteers. The participants will be equally randomized into either green light (treatment) or white light (control) exposure groups. The investigators will initially test the activities of the ascending and descending pathways using thermal and mechanical stimulations. The investigators will also test brain wave activities using a non-invasive EEG device. After establishing the baseline activities of the pain pathways and brain waves, the volunteers will be exposed to the green light or white light at low intensity (4-100 lux) for two hours in our laboratory. After two hours of light exposure, the investigators will again test the activities of the pain pathways using thermal and mechanical stimulation and measure the brain wave EEG activities.
Study design
- Primary purpose
- Basic science
- Allocation
- Randomised
- Intervention model
- Parallel groups
- Masking
- None (open label)
- Number of arms
- 2
| Arm | Type | Receives |
|---|---|---|
| Green Light Exposure | Active comparator | Device: Green Light Emitting DiodeSubjects will complete thermal and mechanical pain threshold detection tests and Electroencephalography (EEG). After completion, subjects will be exposed to a green light-emitting diode for two hours. After exposure, thermal and mechanical pain threshold assessments and Electroencephalography (EEG) will be conducted. |
| White Light Exposure | Placebo comparator | Device: White Light Emitting DiodeSubjects will complete thermal and mechanical pain threshold detection tests and Electroencephalography (EEG). After completion, subjects will be exposed to a white light-emitting diode for two hours. After exposure, thermal and mechanical pain threshold assessments and Electroencephalography (EEG) will be conducted. |
Who may qualify
- Ages
- 18 to 50 years
- Sex
- All
- Healthy volunteers
- Accepted
- Age groups
- Adult
Key inclusion criteria (4 listed)
- 18-50 years healthy men or women
- Able to speak and understand English
- No history of Chronic pain
- No known neuropathies in areas that testing will take place, (forearms, muscle at the base of thumb on the palm of the hand and upper back/shoulder area.
Key exclusion criteria (3 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.
- Colorblindness or uncorrected cataracts.
- Tissue damage in areas that testing will take place, (forearms, muscle at the base of the thumb on the palm of the hand, and upper back/should area.
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 Light Emitting DiodeAlso: GLEDGLED exposure for two hours | Device | Green Light Exposure |
| White Light Emitting DiodeAlso: WLEDWLED exposure for two hours | Device | White Light Exposure |
Primary outcome
Ascending Pain Pathway
Time frame: Two hours
Changes in activity of the ascending pain pathway
Descending Pain Pathway
Time frame: Two hours
Changes in activity of the descending pain pathway
5 secondary outcomes
Delta Brain Activities
Time frame: Two hours
Theta Brain Activities
Time frame: Two hours
Alpha Brain Activities
Time frame: Two hours
Sigma Brain Activities
Time frame: Two hours
Beta Brain Activities
Time frame: Two hours
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 5 Jan 2026.
- Results publication: PubMed 28092651Ibrahim MM, Patwardhan A, Gilbraith KB, Moutal A, Yang X, Chew LA, Largent-Milnes T, Malan TP, Vanderah TW, Porreca F, Khanna R. Long-lasting antinociceptive effects of green light in acute and chronic pain in rats. Pain. 2017 Feb;158(2):347-360. doi: 10.1097/j.pain.0000000000000767.
- Derived from this study: PubMed 40227987Ismail KA, Curfman V, Park J, Louis EM, Korah H, Washington SM, Ibrahim MM, Martin LF. Optimizing Photoneuromodulation Techniques to Evaluate the Role of Green Light-Emitting Diodes in Pain Management. J Vis Exp. 2025 Mar 28;(217). doi: 10.3791/67821.
- 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. This study is not recruiting at the moment.
Mohab 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 Emitting Diode and White Light Emitting Diode in people with Chronic Pain, 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 4 inclusion and 3 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: under way, not looking for participants, as of the sponsor's last update on 5 Jan 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?
The record lists no contact. The official record names the sponsor, who can be asked directly. AzTrials does not enrol participants or take referrals.
What does the primary outcome measure?
Ascending Pain Pathway (time frame: Two hours). The study lists 2 primary outcomes in all. 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 NCT05295225, which also lists 2 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 5 Jan 2026.