Red Light Exposure May Decrease the Risk of Stroke

A new study shows that both humans and mice exposed to long-wavelength red light have lower rates of blood clots that cause heart attacks and stroke, according to research published in the Journal of Thrombosis and Haemostatsis.

Investigators have long correlated light exposure to health outcomes. Because the rising and setting of the sun underlies metabolism, hormone secretion, and blood flow, and heart attacks and stroke are more likely to occur in the morning hours than at night. Therefore, researchers postulated that light may have an impact on the blood clots that lead to these conditions.

To test their hypothesis, the research team exposed mice to 12 hours of either red, blue or white light, followed by 12 hours of darkness, in a 72-hour cycle. Subsequently, they assessed differences in blood clots between the groups. According to the results, the mice exposed to red light had nearly five times fewer clots than the mice exposed to blue or white light.

Moreover, the team analyzed existing data on more than 10,000 patients who had cataract surgery and received either conventional lenses that transmit the entire visible spectrum of light, or blue light-filtering lenses, of which transmit approximately 50% less blue light. The investigators found that that cancer patients who received blue light-filtering lenses had lower risk of blood clots compared to their counterparts with conventional lenses. This finding is notable because cancer patients have nearly 10 times the risk of blood clots of non-cancer patients. These promising findings will now need to be verified through clinical trials.

“These results are unraveling a fascinating mystery about how the light to which we’re exposed on a daily basis influences our body’s response to injury,” said senior author Matthew Neal, M.D., professor of surgery, Watson Fund in Surgery Chair and co-director of the Trauma and Transfusion Medicine Research Center at Pitt, and trauma surgeon at UPMC via a press release. “Our next steps are to figure out why, biologically, this is happening, and to test if exposing people at high risk for blood clots to more red light lowers that risk. Getting to the bottom of our discovery has the potential to massively reduce the number of deaths and disabilities caused by blood clots worldwide.”