Merry Christmas! Green light brings pain relief

Or maybe, it is Mother Nature's greenery goodness, hard-wired into us.

Christmas is not in tinsel and lights and outward show.

The secret lies in an inner glow.

It's lighting a fire inside the heart.

Good will and joy a vital part.

It's higher thought and a greater plan.

It's glorious dream in the soul of man.

- Wilferd Peterson

In this time of Holiday Festivities, we wish all to be of good cheer. And tradition has it, on these dark days, we place bright green lights to glow in the night sky. It paints a pretty picture, but could there be a more therapeutic impetus behind it?

A study, appearing February 2017 journal Pain reported that rats with neuropathic pain that were bathed in green LED tolerated more thermal and tactile stimulus than rats that were not bathed in green LED. Authors then went on to trial green light exposure in their pain clinic patients.

Another study from Duke anesthesiologists:

The researchers studied 34 fibromyalgia patients who were randomized to wear various shades of eyeglasses four hours a day for two weeks: 10 patients wore blue eyeglasses, 12 wore clear eyeglasses and 12 wore green eyeglasses. Patients who wore green eyeglasses were four times more likely to have reduced anxiety than those in the other groups, which saw no reduction in anxiety.

"We found that although their pain scores remained the same, those who wore the green eyeglasses used fewer opioids, demonstrating that their pain was adequately controlled," - Padma Gulur, M.D.

A recent study pursued the mechanisms of action of the analgesia from the color green, in mice. Their focus was on the visual processing system for light perception. They began with study of the rods and cones photoreceptors residing in the outer part of the retina and then the retinal ganglion cells (ipRGC) in the inner part of the retina. By disabling each at different times and then testing how they led to changes in pain experience, they determined that the neural pathway to pain relief began at the photoreceptor step.

Exposure to green light resulted in more downstream GABA signaling, leading to more expression by the Penk gene [encodes for a protein called PENK.] PENK is a precursor for enkephalins, which activates the brain opioid receptors.

A schematic illustration of the mechanisms behind green- light pain relief in mice. Credit: Y.-L. Tang et al, Science Translational Medicine (2022)

In an earlier newsletter, I wrote about the benefits of blue light. Here I pointed out that these light receptors - extra retinal opsins - were residing in tissues and directly absorbing it through skin to manifest its effects.

Can blue light burn up body fat?

But why would green light have an analgesic effect in the first place? What could the evolutionary benefit of such a mechanism be? The Japanese and Chinese cultures practice ‘forest bathing’ where exposure to an environment rich in the color green decreases their physiological and psychological pain. Experiments in psychology did confirm that the color green can convey positive information related to happiness.

“Knowledge is love and light and vision.” - Helen Keller

This previous newsletter more fully explains this connection to the elements of Mother Earth that ground us.

"In the Spring, at the end of the day, you should smell like dirt"

For all of you today I say:

“May your holiday season be one bathed in the light of goodness!”

“If you have knowledge, let others light their candles at it.” - Thomas Fuller

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REFERENCES

Treatment of Pain Gets the Green Light. March 1, 2017. https://news.arizona.edu/story/treatment-pain-gets-green-light

Green eyeglasses reduce pain-related anxiety in fibromyalgia patients, study shows (2022, October 24) https://medicalxpress.com/news/2022-10-green-eyeglasses-pain-related-anxiety-fibromyalgia.html

Yu-Long Tang et al. Green light analgesia in mice is mediated by visual activation of enkephalinergic neurons in the ventrolateral geniculate nucleus, Science Translational Medicine (2022). DOI: 10.1126/scitranslmed.abq6474

‘Forest Bathing’ Is Great for Your Health. Here’s How to Do It. https://time.com/5259602/japanese-forest-bathing/

Gil S, Le Bigot L (2014) Seeing Life through Positive-Tinted Glasses: Color–Meaning Associations. PLoS ONE 9(8): e104291. doi:10.1371/journal.pone. 0104291

MM Hansen et al, Shinrin-Yoku (Forest Bathing) and Nature Therapy: A State-of-the-Art Review. Int J Environ Res Public Health. 2017 Aug; 14(8): 851. doi:10.3390/ijerph14080851