The future of pain management in humans could eventually center less around what people take for their aches and pains and more around what they shine at them. Experimental new research at Stanford University's Bio-X laboratory has found that unconventional light therapy can be used to mitigate chronic pain without the need for pharmaceutical drugs, an amazing breakthrough that has the potential to completely change the way modern medicine deals with pain.

Published in the journal Nature Biotechnology, the new study on light therapy reveals that pain-sensing nerves inside the body can be manipulated to respond in different ways to varying types of light. The glow of a yellow light, for instance, was found to help alleviate pain in mice models, where special light-sensitive proteins known as opsins were injected into the mice and later activated by shining light on them.

"This is an entirely new approach to study a huge public health issue," says Stanford bioengineering professor and Bio-X lab director Scott Delp, lead author of the new study. "It's a completely new tool that is now available to neuroscientists everywhere."

Known as optogenetics, the technique of injecting light-sensitive proteins into the body for the purpose of later using them in therapy was developed by Delp's colleague Karl Deisseroth, who also helped co-author the new study. Deisseroth originally came up with the idea on accident but found that it could be used as a way to activate certain regions of the brain to better understand brain function. As it turns out, this also works in activating or deactivating nerve cells.

After injecting opsins into a group of test mice, Delp and Deisseroth noticed that different lights could be shined onto the mice's paws to induce different pain. Some color temperatures helped alleviate pain in the mice while others actually increased it, a phenomenon that the duo and their other co-authors believe could help explain why some people with no obvious injuries or other conditions suffer from inexplicable pain.

"The fact that we can give a mouse an injection and two weeks later shine a light on its paw to change the way it senses pain is very powerful," says Shrivats Iyer, a Stanford graduate student and co-author of the study.