Exposure to blue light could decrease an individual’s systolic blood pressure by as much as 8 mm Hg in just half an hour, researchers report in a study co-led by the University of Surrey, Heinrich Heine University Düsseldorf and Philips.
The research, published in the European Journal of Preventative Cardiology, exposed 14 healthy men to 30 minutes of monochromatic blue light and another 30 minutes of a control light, or blue light filtered with foil. Co-author Christian Heiss, a professor of cardiovascular medicine at the University of Surrey, and colleagues said in the journal their study explored an alternative to ultraviolet light, which bears a carcinogenic risk.
“Previous studies have shown that ultraviolet light can lead to the release of nitric oxide from the skin and decrease blood pressure,” Heiss et al. wrote. “Here, we investigated whether whole-body exposure to visible blue light can also decrease blood pressure and increase endothelial function in healthy subjects.”
The men Heiss’ team studied were exposed to blue and control lights separately at 450 nanometers each—a dose comparable to daily sunlight. The researchers tracked blood pressure, arterial stiffness, blood vessel dilation and blood plasma levels of nitric oxide throughout the study.
They found that, on average, exposure to whole-body blue light reduced participants’ systolic blood pressure by nearly 8 mm Hg, while the control light had no impact on BP. Blue light was also associated with a decrease in other cardiovascular risk factors, including reduced arterial stiffness and increased blood vessel relaxation.
Perhaps most impressively, the authors found the reduction in BP from blue light was similar to reductions seen in clinical trials with blood pressure-lowering drugs.
“Blue light exposure significantly decrease systolic blood pressure and increased heart rate as compared to control,” Heiss et al. wrote. “In parallel, blue light significantly increased forearm blood flow, flow-mediated dilation, circulating nitric oxide species and nitroso compounds while it decreased forearm vascular resistance and pulse wave velocity.”
The authors said their research supports evidence that light could be used to prevent and reduce instances of cardiovascular disease. In the future, they wrote, physicians should explore applications of blue light, including wearable, all-day sources.