Discover how exposure to intense light may help reduce heart attack risk by enhancing circadian rhythm and boosting protective cardiac proteins.
Researchers at the University of Colorado Anschutz Medical Campus have found that intense light amplifies a specific gene that strengthens blood vessels and may protect against heart attacks.
"We already knew that intense light can protect against heart attacks, but now we have found the mechanism behind it.”
Study’s senior author Tobias Eckle, MD, PhD, professor of anesthesiology, University of Colorado School of Medicine
The study was published recently in the journal Cell Reports.
The scientists discovered that housing mice under intense light for one week robustly enhanced cardioprotection and markedly reduced cardiac tissue damage after a heart attack. They also found that humans might benefit from a similar light-exposure strategy.
To uncover why, they used intense light to target and manipulate the PER2 gene, which is expressed in a circadian pattern in the brain region that controls circadian rhythms.
By amplifying this gene with light, they observed protection of cardiovascular tissues against low-oxygen conditions such as myocardial ischemia.
Light exposure also raised cardiac adenosine, a chemical that helps regulate blood flow.
Mice that were blind showed no cardioprotection, indicating that visual light perception is required.
The team then tested intense light in healthy human volunteers. Participants received 30 min of 10,000-lux light on five consecutive days while researchers collected serial blood samples.
As in mice, PER2 levels rose. Plasma triglycerides, a marker linked to insulin sensitivity and carbohydrate metabolism, fell significantly, suggesting improved metabolism.
Eckle has long studied light’s role in cardiovascular health. He notes that previous work has linked darker winter months to higher myocardial infarction rates across U.S. states, including sunny regions like Arizona, Hawaii, and California. Intensity, rather than duration, appears key.
“The most dramatic event in the history of the earth was the arrival of sunlight,” Eckle said. “Sunlight caused a great oxygen event. With sunlight, trillions of algae could now make oxygen, transforming the entire planet.”
Eckle believes intensive light therapy could become a promising adjunct for treating or preventing low-oxygen conditions such as myocardial ischemia.
If applied before high-risk cardiac or non-cardiac surgery, the therapy might protect the heart muscle from injury, which can be fatal.
“Giving patients light therapy for a week before surgery could increase cardioprotection,” he said. “Drugs that mimic these findings might also be developed. However, future human studies are needed to clarify the impact and potential of intense light therapy for cardioprotection.”
University of Colorado Anschutz Medical Campus
Journal reference:
Oyama, Y. et al. (2019) Intense Light-Mediated Circadian Cardioprotection via Transcriptional Reprogramming of the Endothelium. Cell Reports. doi.org/10.1016/j.celrep.2019.07.020
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