The Effect of Light Therapy on Chronic Pain

  • End date
    Dec 19, 2023
  • participants needed
  • sponsor
    University of Arizona
Updated on 14 February 2022
behavior therapy
chronic pain
back pain
cognitive therapy
pain relieving


Chronic pain is a major problem in the USA and the rest of the world, currently, all available pharmacological interventions carry with them significant side effects. Pain clinics are specially equipped to perform intentional pain procedures to manage pain. However, there remain groups of patients what neither benefit from pharmacological nor from interventional pain procedures. Other methods have shown only minor benefits such as hypnosis or cognitive behavioral therapy. Therefore, other techniques need to be investigated.

Light therapy has been shown to have significant biological effects on humans. For example, light therapy is used to manage depression. Several clinical trials have shown that certain wavelengths of light can improve wound healing, decrease temporomandibular joint dysfunction (TMJ) pain, and decrease fear of back pain. In these trials, light was directed at the site of pain. In an attempt to better understand the effect of different wavelengths of light, pre-clinical studies were conducted using rats. The investigators have shown green and blue Light emitting diode, (LED) light produced antinociception (analgesia) and reversed neuropathic pain associated with several models of chronic pain. The analgesic effect of light was completely blocked when rats had their eyes covered, this suggests that the analgesic effects seen are mainly due to systemic effect through the visual system.

Preliminary experiments on rats suggest that this effect is mediated through the endogenous opioids and cannabinoid system.

The investigators believe that LED light is a safe alternative to pharmacological intervention to manage pain by stimulating the endogenous endorphin and cannabinoid systems. The investigators initial target participants with history of HIV, chemotherapy induced peripheral neuropathy and fibromyalgia. Participants will be divided into 2 groups. The first group will be a control group exposed to white LED light. The second group will be exposed to green LED light, respectively. Participants will be asked to take LED light home and will be asked to set in a dark room for 2 hours daily for 3 months with their LED light on. At the end of the 3 months trial, the investigator will assess their pain intensity, analgesic use, and overall quality of life. The investigators hypothesis is that participants exposed to green and blue light will have less use of analgesics and will have better life quality.


During the initial visit, the investigator will collect several pieces of data from participants that are considered part of the routine care, if you are being seen in the clinic, this information will also be used for research purposes. Initially the investigator will ask participants to provide their age, gender, work status, disability status, type of work, whether a previous pain physician has evaluated or provided treatment in the past, if there is any ongoing litigation, a detailed description of the pain (burning, electrical, shootingetc.) and its location. If the participants are being seen in the clinic for their normal care a detailed physical examination assessing the motor strength of the upper extremities, sensation to light touch and reflexes that is part of the standard of care will be provided for the participants. The participants will be asked to give a numerical value for their pain (a scale from 0-10 where 0 is no pain and 10 is the worst pain imagined). Two questionnaires will be provided for the participants to complete which are not standard of care. The first one is the EuroQol Group (EQ-5D) which provide an over assessment of the quality of life. The second is a medication log to document their analgesics use. If the participants are being evaluated via telephone call, the same questions will be conducted, but no physical exam will be provided.

The participants will be assigned to either a white, or green light group. The participants have 50% chance of being in either group. Once the participants are assigned a light group, the participants will be given a strip of Light emitting diode, (LED) light that correspond to their color group. The participants will be asked to take and use the LED strip in a dark room in their house every day for two hours to be exposed to the light, the participants will do this for 10 weeks. The study start date and the outcome assessment timeline will begin from the date of your first exposure to the assigned light. The participants will be asked to complete their weekly questionnaires and daily log, these will be given to the participants on their first clinic visit or sent to the participants if they live out of town. There will be several follow up appointments as detailed below. There is a chance the participants may be asked to cross over into a different group from the one the participants were assigned, there will we a 2 week washout period, then return to clinic for light assignment then light exposure for 10 week, similar visits as described below.

For the follow up clinic visit or phone call (Week 10), data similar to the information gathered at the initial visit will be collected. The description of the pain (burning, electrical, shootingetc.) and its location will be reviewed. A physical examination assessing for pain and sensation to light touch that is part of the standard of care will be provided for the participants. At the end of the study, the participants will be asked to return the LED strip, their logs and questionnaires.

There is an optional blood draw and saliva sample collection for patients that consent to this. Blood and saliva samples will be collected at baseline and end of study, blood draws will be done to look for inflammatory mediators, increased anti inflammatory mediators and endocannabinoids. Saliva samples will be collected to check for melatonin.

Condition Chronic Pain
Treatment Exposure to green LED light, Exposure to white LED light
Clinical Study IdentifierNCT03677206
SponsorUniversity of Arizona
Last Modified on14 February 2022


Yes No Not Sure

Inclusion Criteria

Adults ages 18 - 80 able to understand English and comply with study protocol
Peripheral neuropathy from HIV or chemotherapy
History of fibromyalgia
Chronic Pain
-day average numeric pain score of 5/10 or greater at baseline evaluation

Exclusion Criteria

Subjects receiving remuneration for their pain treatment
Subjects that are incarcerated
Subjects unable to read English and complete assessments
Addictive behavior, severe clinical depression, or psychotic features
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