Green Light for Pain and Migraine ✳️
The biological effects of light will never cease to amaze us.
For a quick primer on the importance of light, please check out Dan’s TEDx talk, How to Optimize Light for Health (12 min). In fact, exposure to specific wavelengths and intensities of light has shown some beneficial effects in managing various health conditions.
Green light, in particular, has been found to be beneficial for pain relief in rats after nerve injury, and in patients with migraine or fibromyalgia. So can light therapy serve as an effective, non-invasive, and cost-effective option — without the side effects of traditional pain therapies? Let’s take a look at a few related studies below 👀.
This Week’s Research Highlights
✳️ Can green light reduce pain? 🐭
The goal of this recent study was to explore the visual circuits responsible for green light-induced analgesia (pain reduction), and to provide insights into potential strategies for chronic pain management. How did they test this? During the time when mice usually sleep more, they were put in a room with 10 lux of only green light, which is the intensity of candlelight. The researchers confirmed that, indeed, green light did reduce the pain of their arthritis. Next, they identified the light receptors in the retina of the eye responsible for this effect. This Fudan University-based research team in Shanghai used three mouse models in which cones (which help see color), rods (which help eyes adjust to variations in light intensity), or body-clock related, non-visual light receptors (i.e., ipRGCs) were genetically or pharmacologically removed or blocked.
They found that a specific group of retinal ganglion cells (RGCs) relay the signal that underlies the pain relief induced by green light. These RGCs receive mixed inputs from rods and cones but are primarily driven by cones while rods play a secondary role. In fact, the pain reduction was completely abolished in mice deficient in cones, strongly implying cones are key here.
Why? Well, some of the neurons activated by green light project to an area the brain called the DRN (dorsal raphe nucleus) which is an important brain region involved in endogenous descending pain control. So, it seems that green light could very well be a natural pain reducing signal, and this knowledge could potentially be utilized to reduce pain in humans. 🙏🏼
🌿 Exposure to greenspaces could reduce the high global burden of pain.
The relationship between exposure to greenspaces and pain outcomes has not been fully investigated, despite evidence suggesting that greenspace exposure may have a beneficial impact on pain. Studies have found mixed results when investigating the possible association between greenspace exposure and pain or musculoskeletal outcomes. One study, however, investigated the relationship between the percentage of greenspace around the participants' places of residence and health conditions reported in general practice notes in the 12 months prior. The study found significant negative associations between the percentage of greenspace and the number of neck/back complaints, severe back complaints, severe neck/back complaints, and severe elbow/wrist/hand complaints.
🟢 Migraine light sensitivity is driven by cone pathways in the eye.
Migraine headaches are typically made worse by light. Yet recently green light exposure has been shown to effectively reduce the number of headache days in patients with migraine, and reduce pain intensity in patients with fibromyalgia.
In this study, the researchers looked at how the eyes and brain respond to light in people with migraines, and also in rats. They found that green light is least harmful to migraine sufferers when compared to white, blue, amber, or red lights (and previous work has shown green light at low intensities can even alleviated headaches). Why? The green light didn’t activate parts of the eye and brain that make migraines worse as much as other colors do. The findings also suggests that green light has a subjective soothing effect which might explain why people with migraines often prefer green light when evaluated for such preferences.
Random Trivia & Weird News
🧟♀️ The corpse flower (as the name suggests) smells like rotting flesh.
Image from @sandiegobotanicgarden
The Titan arum, also known as the corpse flower, is a large and rare flowering plant native to Sumatra. Despite its unpredictable flowering cycle, advances in horticultural knowledge have allowed botanical gardens to cultivate the corpse flower more widely. When the flower unfurls, tiny male and female flowers at the base of its large central spike emit a putrid odor resembling rotting meat and stinky laundry. Lovely. Mature plants can go years between blooms, adding to the excitement for viewers when blooms do occur.
Podcasts We Loved This Week
- Josh Turknett: Are Migraines Genetic? Via The Migraine Miracle Moment Podcast.
- Stuart McGill: How to Get Rid of Back Pain. Via The Reason & Well-Being Podcast.
Products We Are Enjoying
These glasses by Purple Canyon have green lenses with a color-matching frame and standard fit. Not only might they help with reducing pain and migraine symptoms but at minimum, they are perfect for St. Patricks Day. They have stainless steel hinges, are made from strong PVC, and have scratch-resistant lenses. The manufacturer recommends wearing the glasses for 10 to 30 minutes a day to feel the benefits.
