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Nighttime light exposure and cardiac structure and function
Key result
High nighttime light exposure is linked to ~29% higher heart failure risk and adverse remodelling.
- HR 1.29
- 95% CI 1.12-1.49
- n=73,286
Why the study?
Nighttime light exposure has emerged as a potential risk factor for cardiovascular disease, but its impact on cardiac structure and function remains unknown.
Does high nighttime light exposure increase the risk of adverse cardiac remodeling and incident cardiovascular disease in the general population?
Key Points
- To examine the associations of nighttime light exposure with cardiac structure and function phenotypes, as well as long-term incident cardiovascular diseases and mortality.
- Analyzed 11 071 UK Biobank participants who wore a 7-day wrist accelerometer with an integrated light sensor at baseline (2013–2015) and completed cardiovascular magnetic resonance (CMR) imaging 3 years later.
- Used multivariable generalized linear regression to assess dose-response links between nighttime light (>3 lux) and CMR phenotypes, evaluating mediation by sleep duration.
- Tracked incident cardiovascular outcomes and mortality across 73 286 participants over 8–10 years using multivariable Cox proportional hazards models.
- High versus no nighttime light exposure was associated with 2.4% (95% CI 1.6%, 3.1%) greater indexed LV mass, 1.5% (95% CI 1.0%, 2.0%) greater mean wall thickness, and 1.9% (95% CI 1.1%, 2.7%) lower myocardial contraction fraction.
- Light exposure was associated with impaired myocardial strain across circumferential (−2.7%), radial (−2.9%), and longitudinal (−2.8%) planes, with 24%–49% of structural effects mediated by shorter sleep duration.
- High nighttime light exposure conferred a 29% (95% CI 12%, 49%) higher risk of heart failure, 15% (95% CI 4%, 27%) higher risk of atrial fibrillation, 24% (95% CI 7%, 44%) higher risk of myocardial infarction, 33% (95% CI 11%, 59%) higher risk of stroke, and 26% (95% CI 5%, 52%) higher risk of cardiovascular mortality.
Study Design
Type
Cohort (n=73,286)
Structured PICO
Does high nighttime light exposure increase the risk of adverse cardiac remodeling and incident cardiovascular disease in the general population?
P
Population
73,286 UK Biobank participants who wore a wrist-worn accelerometer with a light sensor for 7 days, followed for 8-10 years for incident cardiovascular outcomes.
E
Exposure
High nighttime light exposure (>3 lux)
C
Comparator
No nighttime light exposure
O
Outcome
Cardiac structure and function (CMR phenotypes) at 3 years, and incident cardiovascular disease outcomes and mortality at 8-10 yearshard clinical
Main Result
Hazard Ratio: 1.29 (95% CI 1.12–1.49)
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Key expert perspectives
Captured external expert commentary on this paper, strongest first. Original sources are linked where available.
“Exposure to light at night can disrupt the body's internal clock and affect the duration and quality of sleep, but this is an observational study, so it cannot prove that nighttime light directly caused the subtle changes in the structure and function of the heart. The links seen do not imply causation nor imply the findings are preventable.”
“It is already recognised that light at night adversely affects animals and insects, thus human harm is not unexpected. It is an interesting and well-conducted study which adds to growing evidence that exposure to light at night is associated with poorer cardiovascular health. A particular strength is that the researchers actually measured individuals' light exposure and then used detailed MRI scans to look at the structure and function of the heart.”
“This is the first study of its kind, and it shows that exposure to higher levels of light at nighttime is linked to cardiac remodelling. This is where the structure and function of the heart changes and we typically see it in response to chronic stress or injury to the heart. It's our body's way of adapting to that stress, but ultimately it weakens the heart and can lead to heart failure.”
Implication
Greater nighttime light exposure is associated with adverse cardiac remodeling and increased risk of incident cardiovascular disease, partially mediated by shorter sleep duration.
Abstract
Background and Aims Nighttime light exposure has emerged as a potential risk factor for cardiovascular disease (CVD). However, its impact on cardiac structure and function remains unknown. Methods This population-based cohort study included 11 071 UK Biobank participants who wore a wrist-worn accelerometer with an integrated light sensor for 7 days between 2013 and 2015 (baseline) and had subsequent cardiovascular magnetic resonance (CMR) imaging 3 years later. Nighttime light exposure >3 lux was estimated, and its dose-response relationships with CMR phenotypes were examined using generalized linear regression models. Associations of nighttime light exposure with incident CVD outcomes and mortality were examined using Cox models (n = 73 286). Results After multivariable adjustment, high (vs none) nighttime light exposure >3 lux was associated with left ventricular (LV) concentric hypertrophy and subclinical functional decline, including 2.4% (95% confidence interval 1.6%, 3.1%) greater LV mass indexed to height1.7, 1.5% (1.0%, 2.0%) greater mean wall thickness, and 1.9% (1.1%, 2.7%) lower myocardial contraction fraction. Nighttime light exposure was also associated with impaired myocardial deformation, including lower absolute global LV circumferential [−2.7% (−3.7%, −1.7%)], radial [−2.9% (−3.9%, −1.8%)], and longitudinal strain [−2.8% (−3.9%, −1.7%)] indices. Adverse associations were also observed for the right ventricle, including 0.9% (0.1%, 1.8%) greater end-diastolic and 1.6% (0.5%, 2.8%) greater end-systolic volumes indexed, and for the left atrium, including 2.3% (0.7%, 3.9%) greater maximum volume indexed and 1.1% (0.3%, 1.9%) lower ejection fraction. All associations exhibited linear dose-response relationships, with most partly mediated by shorter sleep duration (proportion mediated: 24%–49%). During 8–10 years of follow-up, participants with high (vs none) nighttime light exposure had 29% (12%, 49%) higher risk of heart failure, 15% (4%, 27%) higher risk of atrial fibrillation, 24% (7%, 44%) higher risk of myocardial infarction, 33% (11%, 59%) higher risk of stroke, and 26% (5%, 52%) higher risk of CVD mortality. Conclusions Greater nighttime light exposure was associated with adverse cardiac remodelling and subclinical functional decline across multiple chambers, statistically mediated by shorter sleep duration. These findings provide potential mechanistic insights into how nighttime light exposure may elevate CVD risk and highlight dark nights and adequate sleep for cardiovascular health.
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Cite This Study
Dai et al. (2026) conducted a cohort in Cardiovascular disease (n=73,286). High nighttime light exposure >3 lux vs. No nighttime light exposure was evaluated on Heart failure (HR 1.29, 95% CI 1.12-1.49). High nighttime light exposure (>3 lux) was associated with adverse cardiac remodelling and a 29% higher risk of heart failure (95% CI 12%-49%) compared to no exposure.