Green Light Exposure in Healthy Volunteers Exposure in Normal Human Volunteers

Study Overview
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Brief Summary
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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
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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.

Official Title
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Investigating the Analgesic Effects of Green Light Exposure in Normal Human Volunteers

Conditions
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Chronic Pain

Intervention / Treatment
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* Device: Green Light Emitting Diode
* Device: White Light Emitting Diode


Participation Criteria
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Eligibility Criteria
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Inclusion Criteria: 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. Exclusion Criteria: 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.

Ages Eligible for Study
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Minimum Age: 18 Years
Maximum Age: 50 Years

Sexes Eligible for Study
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All

Accepts Healthy Volunteers
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Accepts Healthy Volunteers

Study Plan
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How is the study designed?
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Design Details

Primary Purpose: Basic Science
Allocation: Randomized
Intervention Model: Parallel Assignment
Masking: None (Open Label)


Arms and Interventions

| Participant Group/Arm | Intervention/Treatment |
| --- | --- |
| Active Comparator: Green Light Exposure<br>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. | Device: Green Light Emitting Diode<br>* GLED exposure for two hours<br>* Other names: GLED;|
| Placebo Comparator: White Light Exposure<br>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. | Device: White Light Emitting Diode<br>* WLED exposure for two hours<br>* Other names: WLED;|

What is the study measuring?
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Primary Outcome Measures

| Outcome Measure | Measure Description | Time Frame |
| --- | --- | --- |
| Ascending Pain Pathway | Changes in activity of the ascending pain pathway | Two hours | 
| Descending Pain Pathway | Changes in activity of the descending pain pathway | Two hours | 

Secondary Outcome Measures

| Outcome Measure | Measure Description | Time Frame |
| --- | --- | --- |
| Delta Brain Activities | Changes in the baseline of Delta waves of EEG | Two hours | 
| Theta Brain Activities | Changes in the baseline of Theta waves of EEG | Two hours | 
| Alpha Brain Activities | Changes in the baseline of Alpha waves of EEG | Two hours | 
| Sigma Brain Activities | Changes in the baseline of Sigma waves of EEG | Two hours | 
| Beta Brain Activities | Changes in the baseline of Beta waves of EEG | Two hours |