If you like to fall asleep with the TV glowing in the background or your phone lighting up the nightstand, this new research is a wake-up call for your heart.
A preliminary study presented at the American Heart Association’s 2025 Scientific Sessions followed 466 adults in Boston with no existing heart disease and looked at their exposure to artificial light at night, or nighttime light pollution.
By combining brain scans, artery imaging and satellite data on neighborhood brightness, researchers found a striking pattern: more night-time light was linked to higher stress signals in the brain, more inflammation in the blood vessels, and a greater risk of major heart problems over the next decade.
This isn’t just “light might be bad.” They showed how the brain seems to interpret that extra light as stress. In response, it sends signals that ramp up the immune system and inflame the arteries.
Over time, that chronic, low-level inflammation can harden blood vessels and raise the risk of heart attack and stroke. Even relatively modest increases in night-time light were tied to significantly higher risk.
In fact, every standard deviation increase in light exposure was associated with about a 35% higher risk of heart disease over five years and 22% higher over ten years – even after accounting for traditional risk factors like smoking, blood pressure and neighborhood noise.
People already living with added social and environmental stress, such as high traffic noise or lower-income areas, were hit the hardest.
This is a powerful reminder that heart care is not just about diet and exercise – it’s also about your environment, right down to how bright your bedroom is at night. The upside? Light exposure is something you can actually change.
As study author Dr. Shady Abohashem puts it,
“We found a nearly linear relationship between nighttime light and heart disease: the more night-light exposure, the higher the risk. Even modest increases in night-time light were linked with higher brain and artery stress.”
He suggests very practical fixes: dim or shield outdoor lights, use motion sensors instead of always-on fixtures, and keep bedrooms as dark and screen-free as possible before sleep.
Light pollution is nearly universal in modern cities, and heart disease remains the leading cause of death for women. This research reframes that soft bedroom glow as more than a small annoyance – it’s a modifiable risk factor for your long-term heart health.
If you’ve been looking for one more reason to put your phone away and embrace a darker, calmer bedroom, this is it. Check out the full article on ScienceDaily for all the details and recommendations: Your bedroom glow might be quietly damaging your heart.
