Medical

Light-based pain relief goes green

One of the green-lit enclosures used in the study
One of the green-lit enclosures used in the study
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One group of rats was fitted with contact lenses that allowed only the green spectrum to get through to their eyes
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One group of rats was fitted with contact lenses that allowed only the green spectrum to get through to their eyes
One of the green-lit enclosures used in the study
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One of the green-lit enclosures used in the study

According to the American Academy of Pain Medicine, approximately 100 million people in the US alone suffer from chronic pain. Although opioids (powerful pain relievers) may help, they can cause serious side effects such as dizziness, vomiting and constipation – plus they're addictive. So, what alternatives are there? Well, new research from the University of Arizona indicates that exposure to green light may be another way to go.

Led by Drs. Mohab Ibrahim and Rajesh Khanna, a UA team studied three groups of rats, all of which suffered from neuropathic pain.

One group was placed in clear plastic containers illuminated solely by strips of green LEDs – the lights were on for eight hours a day, over a period of five days. Another group, although lit by regular room light, were fitted with contact lenses (pictured below) that allowed only the green spectrum to get through to their eyes. The third group wore opaque contacts, that didn't let them see light of any color.

One group of rats was fitted with contact lenses that allowed only the green spectrum to get through to their eyes
One group of rats was fitted with contact lenses that allowed only the green spectrum to get through to their eyes

When the animals were subsequently tested, the first two groups exhibited significantly more tolerance for tactile stimulus than the control group. The pain-relieving effect lasted for four days after the light exposure, with no side effects being noted.

Although the reasons for the reaction aren't entirely understood, the scientists believe that it may be because the green light boosts levels of natural opioids circulating within the rats' bodies. Whether or not that effect occurs in humans is another question, which is why a 10-week clinical trial is now being conducted on people with fibromyalgia. Dr. Ibrahim tells us that the results so far are encouraging.

As an interesting side note, a 2016 Harvard study indicated that green light also helps alleviate migraine headaches – again, the reason why wasn't immediately clear.

A paper on the UA research was recently published in the journal Pain.

Source: University of Arizona

6 comments
Racqia Dvorak
Wow. That control group is awful. OPAQUE contact lenses?? So, you're saying that mice left in the dark are more stressed out and sensitive to pain? No normal light control group. You know, there are people out there that look up to scientists and this new generation is quite disappointing.
MichelleJohnson
As a chronic pain patient and an RN, I would be interested in seeing how this would work for me. Taking opioids are not beneficial when I am taking care of patients.
Douglas Bennett Rogers
In the '40s, light green was thought to be a calming color. We got millions of light green metal cube dividers which were handed down to the '80s. They made me nauseous. I was so glad to finally get the orange and blue fabric ones.
JohnBalance
Let's stop mincing words when writing about animal research like this. The way this and many articles are written makes it seem like the researchers were helping the rats. The researchers CAUSE the pain in the rats in these studies either through engineering them to be more sensitive to pain or through injury such as causing head injury, injecting acid into them, etc. This research is cruel and could have easily been safely done in human beings suffering from pain both chronic and acute. I for one would volunteer. Absolutely despicable animal abuse for no good reason other than grant money and sadistic interest.
dburdsal
I believe John Balance should never be given any medicine of any kind that was developed by animal testing... No morphine after a car wreck, no radiation or chemo, nothing. Let's no mince words here, obviously it would be hypocritical of him....
Joe Joseph
I have Fibro, Id love to be in the research, but I am also color deficient with a red-green deficiency. So I can still process green, but it is easy to mix certain colors. I describe it as, I can see primary and secondary colors ok, its the tertiary and blends that I get confused by. So I wonder even if this does work, if it will work for us guys who are color deficient and color blind. On one side I say, it should because even though the rods and cones are not in the correct distribution, the retina is still taking in green light, the brain just doesnt see it that way. On the other hand, the entire science may in fact be based on the fact that the brain can see the proper green as supplied by adequate rods and cones. Of course, lets throw in another variable and figure out if the Enchroma color vision correction glasses would help if color vision is critical to the process. Since they said it was green LED lights, maybe I will just go get a bunch of green LED Christmas lights and set them up in my office.
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