An international team of researchers from the University of Surrey (Surrey, England) and Heinrich Heine University Dusseldorf (Dusseldorf, Germany), in collaboration with Philips (Amsterdam, Netherlands), has found that exposure to blue light decreases blood pressure, in turn reducing the risk of developing cardiovascular disease.
During the study, participants were exposed to 30 minutes of whole-body blue light at approximately 450 nm, a dose comparable to daily sunlight—followed by exposure to a control light on a different day. Visible blue light, as opposed to UV light, is not carcinogenic. To assess the impact, participants' blood pressure, stiffness of arteries, blood vessel dilation, and blood plasma levels of nitric oxide stores were measured before, during, and up to two hours after irradiation with both lights.
The researchers discovered that exposure to whole-body blue light significantly reduced the systolic blood pressure of participants by almost 8 mmHg, compared to the control light that had no impact. The reduction of blood pressure from blue light is similar to what is seen in clinical trials with blood pressure-lowering drugs.
Besides blood pressure-lowering effects, the research team also uncovered that exposure to blue light improved other cardiovascular risk markers, including reduction of arterial stiffness and increasing blood vessel relaxation. This further supports that light could be used to prevent cardiovascular disease.
Researchers also found that exposure to blue light increased levels of nitric oxide, which is an important signaling molecule that protects the cardiovascular system. It is believed that blue light releases from the skin into the bloodstream, where it relaxes the blood vessels—increasing blood flow and decreasing blood pressure.
"Wearable blue light sources could make continued exposure to light possible and practical," says Christian Heiss, professor of cardiovascular medicine at the University of Surrey and a National Health Service (NHS; London, England) consultant. "This would be particularly helpful to those whose blood pressure is not easily controlled by medication, such as older people."
Full details of the work appear in the European Journal of Preventative Cardiology.