Шөнийн турш гэрлийн нөлөөнд байх нь зүрхний бүтэц, үйл ажиллагаанд өөрчлөлт оруулж, зүрх судасны өвчлөлийн эрсдэлийг нэмэгдүүлж болзошгүйг Tulane их сургуулийн судлаачид тогтоон, European Heart Journal сэтгүүлд 2026 оны есдүгээр сарын 9-нд нийтэлжээ.
Судлаачид Их Британид 2013-2015 оны хооронд 11,000 гаруй насанд хүрэгчийн бугуйндаа зүүсэн гэрэл мэдрэгч төхөөрөмжийн өгөгдлийг ашиглан тэдний шөнийн гэрлийн өртөлтийг хэмжсэн байна. Шөнийн цагаар 3 люксээс дээш гэрэлд өртөх нь нойр-сэрүүн байдлыг зохицуулдаг мелатонин дааврыг дарангуйлах боломжтой гэж үзжээ. Гурван жилийн дараа хийсэн зүрхний MRI шинжилгээгээр шөнийн гэрлийн өндөр өртөлттэй хүмүүсийн зүрхний зүүн ховдлын масс 2.4 хувиар их, зүрхний хана 1.5 хувиар зузаан, булчингийн агшилтын үзүүлэлт 1.9 хувиар буурсан болох нь илэрсэн байна.
Шинжилгээгээр шөнийн гэрэлд их өртөх нь зүрхний дутагдал, тосгуурын фибрилляци, зүрхний шигдээс, цус харвалт болон зүрх судасны өвчнөөр нас барах эрсдэлийг 15-33 хувиар нэмэгдүүлж болохыг 73,286 хүнийг хамарсан өргөн хүрээний бүртгэлээс тогтоожээ. Мөн гэрлийн өндөр өртөлттэй бүлгийнхэн дунджаар 6.9 цаг унтаж байсан бол гэрэлд өртөөгүй бүлгийнхэн 7.7 цаг унтдаг байсан нь нойрны үргэлжлэх хугацаа зүрхний бүтцийн өөрчлөлтөд нөлөөлж буй нэг хүчин зүйл байж болохыг харуулж байна.
Гэсэн хэдий ч судлаачид энэ нь шууд шалтгаант холбоо гэдгийг баталж чадахгүй гэдгийг онцолжээ. Судалгаанд оролцогчдын нас, хүйс, тамхи таталт, таргалалт зэрэг хүчин зүйлсийг тооцсон хэдий ч хэмжигдээгүй бусад нөлөөлөл байж болох ба судалгаа нь зөвхөн ажиглалтад суурилсан тул гэрлийн өртөлтийг бууруулснаар зүрхний өвчнөөс урьдчилан сэргийлэх боломжтой эсэхийг хараахан нотлоогүй байна.
Дэлгэрэнгүйг эх сурвалжаас харах
↓Эх сурвалжийг нээх ↓
More than 11,000 adults in the United Kingdom wore wrist-mounted light sensors for one week between 2013 and 2015, giving researchers a detailed record of their nighttime light exposure. The devices measured surrounding light minute by minute and were worn for a median of 23.8 hours a day. None of the participants had known cardiovascular disease when the study began.
Researchers led by a team at Tulane University focused on the least active five-hour period of each participant’s day as a proxy for nighttime. They measured how much time people spent exposed to light above 3 lux, a level the researchers said may be sufficient to suppress melatonin, the hormone involved in regulating the sleep-wake cycle.
About three years later, participants underwent cardiac MRI scans. Those with the highest exposure to light at night had 2.4% greater left ventricular mass than people who recorded no exposure above 3 lux, with a 95% confidence interval of 1.6% to 3.1%. Their heart walls were also 1.5% thicker, while one measure of heart muscle contraction was 1.9% lower.
The study was published on September 9, 2026, in the European Heart Journal. The authors describe it as the first research to examine nighttime light exposure using cardiac MRI, providing a closer look at possible links between sleep environments and heart health.
About 34 Minutes of Light a Night
More than one-quarter of participants recorded no nighttime light above 3 lux and served as the reference group. The others were divided into low-, intermediate- and high-exposure groups. People with the greatest exposure averaged 33.9 minutes above the threshold during their nighttime window.
Other heart measurements showed similar differences. Three measures of left ventricular strain, which indicate how the heart muscle changes shape as it contracts, were 2.7% to 2.9% lower in the highest-exposure group. Maximum left atrial volume was 2.3% larger, while left atrial ejection fraction was 1.1% lower.
The associations generally followed a linear dose-response pattern, meaning cardiac differences increased as nighttime light exposure rose. Previous research has also connected light at night with cardiovascular health, including a 2025 JAMA Network Open study involving nearly 89,000 adults and a 2022 laboratory study that found a higher heart rate after sleeping under moderate room light.
Shorter Sleep May Explain Part of the Link
Sleep duration differed substantially between the groups. Participants with the highest nighttime light exposure slept an average of 6.9 hours, compared with 7.7 hours among those with no exposure above 3 lux. Researchers therefore examined whether shorter sleep could partly explain the relationship between nighttime light and changes in heart structure.
Of 24 cardiac measures associated with light exposure, sleep duration statistically mediated 16. Shorter sleep accounted for an estimated 24% to 49% of these relationships, including 49% of the association with relative wall mass, 41% with maximum wall thickness and 39% with the thickness of the wall separating the ventricles.
These results point to sleep as one possible pathway linking nighttime light exposure with heart health, but they do not prove that reduced sleep caused the cardiac differences. Mediation analyses depend on assumptions about other factors that may affect both sleep patterns and cardiovascular health.
Heart Failure, Stroke and Other Cardiovascular Risks
The researchers also examined hospital and death records in a larger group of up to 73,286 adults, depending on the outcome, over roughly eight to ten years. Compared with people who recorded no nighttime light above 3 lux, those with the highest exposure had a 29% higher risk of heart failure and a 15% higher risk of atrial fibrillation.
The high-exposure group also had a 24% higher risk of myocardial infarction, a 33% higher risk of stroke and a 26% higher risk of cardiovascular death. For heart failure specifically, the age- and sex-standardized rate was 361 cases per 100,000 person-years in the highest-exposure group, compared with 218 in the group with no exposure.
What the Study Cannot Prove
The findings show an association between light at night and cardiovascular risk, not proof that nighttime lighting directly damages the heart. People in the highest-exposure group were more likely to be male, smoke or have obesity, and seasonal differences also existed between groups. Researchers adjusted for these factors, as well as age, diet, air pollution and daytime light exposure, but unmeasured influences may remain.
The researchers also tested whether existing heart differences could have influenced later light exposure. Removing participants whose cardiac MRI occurred within two years of light monitoring did not erase the associations. Among 951 people whose MRI came before light monitoring, no cardiac measurement significantly predicted later nighttime light exposure after correction for multiple testing.
The study has other limitations. Participants had an average age of 61 and were 97.6% White, while light exposure was recorded for only seven days. The sensors measured light intensity but could not determine whether it came from a television, smartphone, bedside lamp, streetlight or another source.
Overall, the findings add to growing research on the relationship between nighttime light, sleep and cardiovascular health. Shorter sleep may account for part of the association, but the study does not show that reducing light exposure at night can prevent heart disease.
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