Scientists Warn This Hidden Nighttime Danger Can Lead to Heart Disease
Spending screen-free time before bed can improve sleep performance, but to reap the full benefits, you’ll actually want to reduce all types of night light exposure. A study out of China found that increased exposure to artificial outdoor light puts people at a 43 percent higher risk of cerebrovascular disease. Now, scientists are corroborating this claim with new research that shows nighttime exposure to bright lights and even our phones can lead to heart attack, stroke, and more.
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Night light exposure can disrupt sleep quality and heart health.
Studies show that late-night doomscrolling can take a toll on both your mental health and sleep quality. But did you know that it could also increase your risk of heart disease? A new research paper shared on medRxiv illustrates that “personal night light exposure” triggers circadian disruption, which is a known risk factor for five major cardiovascular events, including:
- Coronary artery disease
- Heart failure
- Stroke
- Myocardial infarction (heart attack)
- Atrial fibrillation (commonly referred to as AFib)
“Personal night light exposure” can refer to both outdoor and indoor light sources. As for the latter, this can encompass nightlights, reading lamps, and blue light emitted from electronic devices, including our phones.
We know that blue wavelengths have the power to “suppress” the production of melatonin, a hormone that “influences” circadian rhythm, per Harvard Health.
Thus, by offsetting your circadian rhythm, you’re also inadvertently elevating your risk for heart disease. Let’s unpack the study even further.
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High levels of light exposure at night can increase heart attack risk up to 65 percent.
The study looked at 88,905 UK Biobank participants (over the age of 40) who wore light-tracking devices on their dominant wrist for one week. During a nine-year follow-up period, researchers tracked incidences of heart disease. These were captured via hospital admissions, primary care visits, self-observations, and death records.
Before the data analysis, the team adjusted their findings to account for risk factors such as physical activity, smoking, alcohol intake, diet, sleep duration, and socioeconomic status.
They concluded that “exposure to brighter light at night predicted higher incidence of coronary artery disease, myocardial infarction, heart failure, atrial fibrillation, and stroke, independent of established cardiovascular risk factors.”
In a comparison analysis, researchers examined sleep and health data from people with the brightest nights (90 to 100th percentiles), compared to people with the darkest nights (0 to 50th percentiles). Unsurprisingly, those in the high percentiles were more at risk for suffering a major cardiovascular event.
Here is how the “brightest nights” group stacked up against their peers:
- 23 to 32 percent higher risk of coronary artery disease
- 45 to 65 percent higher risk of heart attack
- 28 to 30 percent higher risk of stroke
- 45 to 56 percent higher risk of heart failure
- 28 to 32 percent higher risk of AFib
They also found:
- Women with high exposures to night light were at an increased risk of heart failure and coronary artery disease
- Younger individuals with high exposures to night light were at an increased risk of heart failure and AFib
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The takeaway:
Disrupting your circadian rhythm with long-term night light exposure can put you at an increased risk of coronary artery disease, heart failure, stroke, heart attack, and AFib.
If you have a habit of late-night TV binging or doomscrolling, try picking up a book instead. Alternatively, you can use the last hour before bed to journal, meditate, stretch, knit, or catch up on your favorite podcast/audiobook.