A preliminary analysis from Boston researchers ties greater exposure to artificial light at night to heightened stress activity in the brain, arterial inflammation, and a higher risk of major heart events. The work will be presented at the American Heart Association’s Scientific Sessions 2025 in New Orleans on November 7–10 and frames light pollution as a potentially modifiable environmental factor.
Methods and cohort
- Investigators at Massachusetts General Hospital reviewed records for 466 adults (median age 55) who underwent PET/CT imaging between 2005 and 2008. Participants had no diagnosed heart disease or active cancer at baseline. Nighttime light exposure at each home address was estimated using the 2016 New World Atlas of Artificial Night Sky Brightness, which models ground-level sky brightness from human-generated sources, and outcomes were tracked through 2018, according to an American Heart Association news release.
Key findings
- Higher artificial light at night was associated with increased stress-related activity in the brain, signs of arterial inflammation, and a greater likelihood of major heart events.
- Risk rose with exposure: each standard-deviation increase in nighttime light was linked to about a 35% higher risk of heart disease over five years and 22% over 10 years, after accounting for traditional risk factors and socio-environmental measures such as noise and neighborhood socioeconomic status.
- During follow-up, 79 participants (17%) experienced major heart problems. Risks were higher among those living amid additional stressors (for example, heavy traffic noise or lower neighborhood income).
What researchers and experts say
- “We found a nearly linear relationship … the higher the risk,” said senior author Shady Abohashem, M.D., M.P.H., head of cardiac PET/CT imaging trials at Massachusetts General Hospital and an instructor at Harvard Medical School. He added that modest increases in night light were linked with greater brain and artery stress, and suggested steps such as shielding streetlights or using motion-sensitive lighting, and keeping bedrooms dark while limiting screens before bed.
- “These findings are novel and add to the evidence suggesting that reducing exposure to excessive artificial light at night is a public health concern,” said Julio Fernandez-Mendoza, Ph.D., of Penn State College of Medicine, who was not involved in the research.
Context and caveats
- The analysis is observational and based on previously collected data, so it cannot prove causation. It reflects a single health system and a largely white cohort (about 90%), which may limit generalizability.
- The findings are being presented as a meeting abstract and have not yet been published in a peer‑reviewed journal.
Conference details
- The American Heart Association’s Scientific Sessions 2025 are scheduled for November 7–10 at the Ernest N. Morial Convention Center in New Orleans.
