We’ve historically thought about light exposure at night mainly in the context of sleep quality or insomnia. 

Now, a growing body of research suggests there’s more to it than “sleep hygiene” boost: light in your bedroom at night, even relatively dim or ambient light, may be quietly raising your risk of cardiovascular disease up to 50%, including heart attacks, stroke, and heart failure. This idea might feel surprising at first, but recent data illuminate literally and figuratively, how our modern lighting environment can subtly influence heart health.  

This article breaks down how it appears to affect your physiology, and practical ways to minimize risk without overhauling your life. 

Bedroom Light and Heart Disease, What We’re Learning 

A large cohort study of nearly 88,905 adults tracked by researchers over roughly a decade found a consistent and independent association between nighttime light exposure and increased risk of multiple forms of cardiovascular disease, including coronary artery disease, heart attack, stroke, heart failure, and irregular heartbeat. These associations remained even after adjusting for classic risk factors such as smoking, high blood pressure, diet, physical activity, and sleep duration.  

To put this into perspective: 

• People with the highest light exposure at night had significantly higher risks across several serious outcomes compared with those in the darkest sleeping environments. (
• For example, some analyses showed up to a 47–56% increase in heart attack and heart failure risk among those exposed to the brightest nighttime light compared with the darkest sleepers. 

• Other cardiovascular outcomes, like coronary artery disease and stroke, were also significantly more likely in the highest nighttime light exposure groups. 

Importantly, this relationship appears dosedependent: generally, the more light you’re exposed to at night, the higher the cardiovascular risk. 

How Bedroom Light Might Affect the Heart 

The heart isn’t directly “seeing” light, but your biological clock is. Here’s how researchers think the link works: 

1. Disruption of Circadian Rhythms

Humans evolved to operate on a roughly 24-hour cycle, a circadian rhythm synchronized by natural daylight and darkness. Darkness signals the brain to produce melatonin, a hormone that promotes sleep and influences many other biological processes, including cardiovascular regulation. 

When your body is exposed to light at night from lamps, streetlights through windows, TVs, or phone screens that cues the brain that it’s not truly nighttime. This disrupts the internal clock, leading to misalignment in hormone release, blood pressure regulation, and metabolic functions.  

2. Elevated Stress Signals and Inflammation

Some studies suggest that light during sleep may trigger subtle stress responses in the brain, which in turn can lead to inflammation in blood vessels, one of the fundamental drivers of cardiovascular disease. This inflammatory stress can contribute to vessel hardening, higher blood pressure, and other mechanisms that over time increase the chance of heart attack and stroke.  

3. Poor Sleep Quality and Metabolic Effects

Light in the sleep environment also interferes with sleep quality, even subtle, subconscious disruptions can blunt the body’s ability to repair itself overnight. Poor sleep has well-established links with insulin resistance, obesity, and hypertension, all of which are cardiovascular risk factors in their own right. 

Which Types of Light is Best? 

Not all nighttime light is created equal, but several common sources can contribute to risk: 

• Indoor lights left on overnight, from lamps to overhead lighting. 

• Streetlights or porch lights filtering through windows. 

• Screens such as TVs, computers, smartphones, especially blue-rich light that most affects circadian signaling. 

• Nightlights that aren’t carefully chosen or positioned. 

Even relatively moderate lighting levels,  not just glaring bulbs, may influence heart health, according to multiple studies. 

Interestingly, the timing of exposure matters, too. Bodies are especially sensitive to light signals between midnight and early morning, a period when physiological processes responsible for blood pressure regulation and hormone production are usually at rest. 

Who Might Be Most at Risk? 

Research suggests that the cardiovascular consequences of nighttime light exposure may not affect everyone equally: 

• Women and younger adults in some analyses appeared to show stronger associations between night light exposure and certain cardiovascular outcomes. 

• People living in urban or high light-pollution environments who may be exposed to streetlights or glow from nearby buildings could experience higher baseline exposure. 

• Those with pre-existing sleep disruptions or irregular sleep patterns could be more vulnerable to the combined effects of light and circadian disruption. 

However, the evidence is still evolving, and risk isn’t limited to any single group, nearly everyone is affected by circadian signaling to some degree. 

How to Protect Your Heart Through Better Bedroom Lighting 

You don’t need to live in total darkness to benefit, but research strongly suggests that reducing light exposure during sleep is a simple step toward better cardiovascular health. 

Here are science-informed strategies: 

1. Darken Your Sleep Environment

Close curtains or blinds to block external light. Consider blackout curtains if street or porch lights seep into your room. 

2. Turn Off Lights Before Bed

Even dim overhead lights can disrupt circadian rhythms. Turning them off ensures darkness during your deepest sleep stages. 

3. Shift Screens Earlier

Screens emit blue light, which is particularly potent in suppressing melatonin. Try to avoid phone or tablet use at least an hour before bedtime. 

4. Choose Gentle Night Lighting When Needed

If you truly need a light for kids, safety, or comfort  opt for a low-intensity, warm-colored light placed away from direct line of sight. 

5. Be Consistent with Sleep Timing

Consistent sleep–wake schedules strengthen circadian rhythms and may counteract some of the disruptive effects of nighttime light. 

These adjustments are low-cost, easy to implement, and supported by research as potential ways to lower cardiovascular risk associated with bedroom light exposure. 

The information on this website is meant to educate, not replace medical advice. Before you make any changes to your diet, lifestyle, or exercise routine based on what you read here, talk to a qualified healthcare professional who can evaluate your personal health and give you proper guidance.