A new study led by researchers from the University of Pittsburgh School of Medicine and UPMC has found that exposure to long-wavelength red light may help reduce the risk of dangerous blood clots.
These clots can lead to serious health problems like heart attacks, strokes, and lung damage.
The findings, published in the Journal of Thrombosis and Haemostasis, suggest that red light therapy could become a low-cost way to help prevent blood clots and save lives.
Dr. Elizabeth Andraska, the study’s lead author, explained that the type of light we’re exposed to can influence our biological processes. Light affects everything from sleep and metabolism to hormone levels and blood flow.
Previous research has shown that heart attacks and strokes are more common in the morning, suggesting that natural light cycles play a role in how our bodies respond to health risks.
To test how different kinds of light might affect blood clotting, the research team exposed mice to cycles of red, blue, or white light—12 hours of light followed by 12 hours of darkness—for three days.
They found that the mice exposed to red light had nearly five times fewer blood clots than the mice exposed to blue or white light. The red light didn’t affect the animals’ sleep, eating habits, weight, or temperature, making it a safe option.
The researchers also looked at data from more than 10,000 patients who had cataract surgery. These patients received either standard lenses that allow all visible light to pass through, or special lenses that block about half of the blue light.
Cancer patients with blue light-filtering lenses had a lower risk of blood clots compared to those with regular lenses. Since cancer patients are already at a much higher risk for blood clots, this finding is particularly important.
Senior author Dr. Matthew Neal emphasized the potential impact of the discovery. He said the next step is to figure out why red light lowers the risk of clotting and to see whether exposing high-risk people to more red light could offer protection.
Interestingly, the benefits of red light were not seen in blind mice, nor did simply shining red light on blood directly change clotting. This shows that the effect likely involves the brain’s optic system, not just the blood itself.
Further studies showed that red light exposure may reduce inflammation and immune system activity that can lead to clot formation.
Mice exposed to red light had fewer NETs—sticky webs made by immune cells to catch germs, but which also trap platelets and form clots. Red light also boosted the production of fatty acids, which help prevent platelets from becoming too active.
These findings could eventually lead to better treatments or medications for preventing clots. The team is now preparing for clinical trials and developing red light goggles that can safely deliver controlled amounts of light to human volunteers. They are also working to identify which groups of people might benefit the most from this kind of therapy.
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The study is published in Journal of Thrombosis and Haemostasis.
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