What color is pain relief? A study from the University of Arizona in Tucson suggests green — at least when it comes to migraines.

Previously, researchers discovered that green light could lead to pain relief in laboratory rats. Now, researchers are exploring the healing hue as a preventive treatment for people who experience migraines.

A migraine is a headache of extreme intensity and can cause symptoms that interfere with daily activities, such as throbbing pain, intense nausea, vomiting, and heightened sensitivity to light and sound.

For some, a migraine can last for a couple hours. For others, it can be days.

Although pain relief can be found through some medications, people can experience unwanted side effects or minimal effectiveness.

Study participants fell into two categories: those who had episodic migraines, or up to 14 headache days per month, and chronic migraines, 15 or more headache days per month for three or more months.

At first, the participants spent one to two hours every day in a dark room with a white light strip, which served as a control condition. After 10 weeks of the white lighting, participants stopped for two weeks as part of a “washout” period.

Then, for another 10 weeks, participants spent one to two hours daily with a strip that emitted green light, at the same brightness level as the white. On average, the green light treatment resulted in fewer migraines experienced.

More study is needed to replicate the light’s effects in a larger participant pool and account for the placebo effect. But the early results could be a green light on the way to migraine relief.