In recent years, studies in rodents and humans have suggested that exposure to light may reduce chronic pain. Green light, in particular, has been reported to relieve pain in people with migraines and fibromyalgia. However, little is known about the mechanism behind these observations. A study published yesterday (December 7) in Science Translational Medicine unravels part of this mystery: The researchers conclude that in mice, this green light analgesia is mediated mainly by cones, the photoreceptor cells in the eye responsible for detecting color and, to a lesser extent, by rods, another photoreceptor in the eye. They also pinpoint a subset of neurons in a thalamic structure involved in this effect.
This study is important because it confirms observations of green light-mediated analgesia that were previously made by other, independent groups—“something that only very few groups in the world . . . have looked at,” says University of Arizona anesthesiologist ...
