We live in a world bathed in artificial light, from smartphone screens to street lamps, well past sunset.
While we’re told to watch our diets, move more, and manage stress, a lesser-known threat to cardiovascular health is silently at work in the dark hours.
Emerging research demonstrates that exposure to artificial light at night may trigger biological responses that raise heart disease risk.
The reason this matters lies in the body’s circadian rhythm, the internal clock that regulates sleep-wake cycles, hormone release, metabolism and cardiovascular dynamics.
When artificial lighting extends or shifts the period of perceived daytime, it confuses the brain’s master clock and sends false signals to the rest of the body.
In one large observational study covering tens of thousands of adults, higher levels of artificial outdoor light at night correlated with increased risk of major cardiovascular events including coronary disease, heart attack, heart failure, and stroke.
The risk appears to grow in a nearly linear fashion with greater night-time exposure, suggesting that the more light during sleep or rest, the higher the cardiovascular burden.
So what can you do about this risk in your own life? The most effective step is to reclaim your night environment. Create a sleep space that is genuinely dark and quiet.
Draw blackout curtains, turn off unnecessary lights, use warm-colored bulbs in the evening, and limit screen use before bed so your body receives the natural signal that night is time to rest.
Avoiding bright exposures in the hour before bed helps preserve melatonin release and supports normal circadian regulation.
If you live in an area where street lighting or neighbor’s lights intrude into your sleep space, using an eye mask or repositioning your bed may make a meaningful difference.
Beyond your bedroom, consider broader lifestyle practices that support circadian health: keeping consistent bedtimes, waking at the same time daily, and aligning meals and physical activity with daylight hours.
These habits not only promote better sleep quality but also reinforce the synchrony between your internal clock and external environment.
While light at night is only one of many factors in cardiovascular risk, it is a modifiable one that often goes unnoticed.
By taking control of your nights you are also protecting your days—your heart, your vessels, your long-term health.