At TheraSpecs, we’re always excited to see research on how light impacts migraine, so the research on green light and migraine has piqued our interest.
There are two primary areas of research on green light and migraine: acute relief during a migraine attack and a preventive treatment to reduce migraine frequency and severity. One set of researchers tested to see which colors of light were most and least problematic for people with migraine—they unexpectedly found that a small portion of participants experienced relief from exposure to green light during untreated migraine attacks. The other set of researchers are currently exploring green light as a preventive therapy for migraine, though that research has yet to be published.
We take a deeper look at the research and answer key questions about green light as it relates to migraine.
Green Light for Acute Migraine Relief
This study, published in 2016, looked at whether different colors of light could increase migraine pain during a migraine attack.1 Every color of light increased the discomfort of most study participants. The brighter the light, the more discomfort they felt. However, researchers were surprised to find that approximately 20% of the study’s 41 participants said they found green light to have a therapeutic effect. The “findings were personal. Not all patients found green light to be the least painful,” according to one of the researchers, Harvard professor Rami Burstein, PhD, but a portion did find some relief.
The study was conducted by putting participants in a darkened room during an active, untreated migraine attack. (Those participants made an impressive sacrifice for research!) Researchers then turned on different colors of light one at a time and assessed how participants responded. For each color, researchers increased the brightness of each light slowly to see how participants responded to that color of light at different intensities. This is how they determined that about 20% of people find some relief with low-intensity green light. (You can read more about this study in our blog post, Does green light provide migraine relief?)
As with prior studies on light and photophobia, this research found that blue light causes the most pain related to light sensitivity, so reducing to exposure to blue light is a helpful way to get migraine relief. In addition, fluorescent lights have invisible pulsing in the spectrum of green light that this study found to provide relief for some participants. If you are sensitive, you will still want to avoid exposure to the green light found in fluorescent lighting.
Green Light Therapy for Migraine Prevention
In the study that made the news in late 2019, participants spent one to two hours each evening in a dark room that was lit only by a low-intensity green light to see if exposure to the green light could reduce migraine frequency.2 This is the only light they could be exposed to, so they couldn’t use screens like televisions, phones, computers, tablets, or e-readers. Because researchers believe the green light has to enter the eyes to be therapeutic, participants were encouraged to do something engaging so they wouldn’t fall asleep, like read, have a conversation, or do a hobby that doesn’t require a lot of light. Since the researchers knew that light can be uncomfortable during a migraine attack, they told participants to only use the light between migraine attacks.
The study results have not been published, so researchers don’t know for sure how effective the therapy will be for participants. The lead researcher said that of the participants he’s checked in with, about 60% told him they had some at least some reduction in the frequency of their migraine attacks during the study. He is expecting that about 30 participants will complete the study. Since the study hasn’t been completed yet, we won’t know what the data will show until all the analysis is finished.
The researchers are aware that sitting in a mostly dark room for an hour or two each day may be too restrictive for some people; and in fact, excessive time in a dim or darken space is something to be avoided if you have light sensitivity. They hope to do further research to see if participants can get benefits from shorter, less restrictive exposure.
(You can learn more about this study in Green Light Therapy for Migraine, an article I wrote for Migraine.com after interviewing the lead researcher of the study.)
Is green light therapy worth trying?
With so few studies conducted on green light for migraine and such small numbers of participants in the studies (41 in the first, about 30 in the second), it’s too early to know if green light therapy will be effective for many people. Also, the second study required a significant time commitment that may not be not be feasible for everyone. That said, it falls into the category of something that’s worth talking to your doctor about trying because it’s unlikely to have side effects and it might help.
What about glasses with green lenses?
Green lenses based on the research findings aren’t currently for sale because green light therapy is very different from glasses. Green light therapy is intended to expose you to the potentially least painful wavelengths of light in an isolated space for a specified period of time. The research on green light used a very narrow band of green light at a low intensity. Glasses that exposed you to only that light would be incredibly dark—darker than regular sunglasses. Blocking that much overall light would likely provide relief, but it would also increase your sensitivity to light over time through a process called dark adaptation.
1Noseda R, Bernstein CA, Nir RR, et al. Migraine photophobia originating in cone-driven retinal pathways. Brain. 2016;139(Pt 7):1971–1986. doi:10.1093/brain/aww119
2Smyres, Kerrie. "Can Green Light Therapy Reduce Migraine Attacks?" Migraine.com. 22 January 2020. Accessed on March 12, 2020 at https://migraine.com/living-migraine/green-light-therapy/