Green is good

A shade of green light has been found to soothe pain in migraine patients

26 May 2016 by Olivia Wannan

A special pair of ‘green-tinted glasses’ could be just the trick for migraine sufferers, an early-stage study suggests.

The new research, published in the journal Brain, concluded that a narrow band of green light was preferred to other colours of light by people experiencing migraine. Dimmer levels of green light even reduced the pain of some of the 69 patients in the Harvard Medical School study.

The patients took part in the trial while they were experiencing an untreated migraine. After sitting in the dark before and in between each experiment, each participant was exposed to gradually rising levels of different-coloured light – from white to blue, green, amber and red.

All were asked to rate the intensity of their headache, its location and related symptoms over this period. Migraine intensity typically increased with rising levels of all colours of light – except green, the researchers discovered.

It was an “unexpected” finding that the colour reduced the pain of approximately one in every five patients, research co-author and Harvard Medical School neuroscience and anaesthesia professor, Dr Rami Burstein, told OT.

He explained: “We expected blue to be most painful, based on our previous paper in Nature Neuroscience. We did not expect green to be the least painful or even pleasant. We are currently trying to figure out why.”

But before migraine sufferers rushed out to buy green spectacles, Dr Burstein warned: “To be used by migraine patients, we need to develop low-cost lenses that will filter out all but a very narrow band of green light. For us, the current cost of one such lens is $1500–2000 (£1020–£1360).”

In conjunction with studying the brain cells of rats, the researchers looked at the intensity of the electrical signals generated by the patient’s retina and their brain’s visual systems in response to the various colours.

This work suggests that the way the light activates the cones in the retina and is fine-tuned by the visual brain cells may help to explain why green light has a different effect on headaches.


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