Infographic: Artificial Light at Night & Breast Cancer Risk – In our modern world, exposure to artificial light at night (ALAN)—from streetlights to smartphone screens—is nearly unavoidable. But could this seemingly harmless light be affecting our long-term health?
Published on May 5, 2025
Dr. Mortazavi recently summarized these findings: Dr. Alireza Mortazavi – LinkedIn Post on Breast Cancer, Blue Light, and Public Health
Infographic: Artificial light at night & breast cancer risk, highlighting both global studies and the early work by Mortazavi et al. Several studies have found links between exposure to artificial light at night—especially blue light from screens—and increased breast cancer risk, particularly in genetically predisposed women.
Artificial Light at Night & Breast Cancer Risk: What Does the Science Say?
Recent studies suggest a concerning link between nighttime light exposure and breast cancer risk, though the strength of evidence varies.
Global studies and the early work by Mortazavi et al.
- Kloog et al. (2011) found that higher levels of outdoor ALAN correlate with increased breast cancer incidence.
- Männisto et al. (2021) highlighted smartphone screen exposure as a potential risk factor, though direct large-scale studies are still limited.
- He et al. (2022) conducted a meta-analysis showing a moderate positive association between ALAN and breast cancer risk.
- James et al. (2017) linked both indoor and outdoor artificial light to higher risk, especially in younger women, using nurse cohort data.
- Garcia-Sánchez et al. (2018) found an association between tablet use in the bedroom and increased breast cancer risk, supporting concerns around digital screens and circadian disruption.
Mortazavi et al. (2018–2024) contributed valuable research on blue light, screen time, and machine learning models predicting breast cancer risk—offering insights but calling for further studies.
- Mortazavi SAR, Tahmasebi S, Lech JC, Welsh JS, Taleie A, Rezaianzadeh A, Zamani A, Mega K, Nematollahi S, Zamani A, Mortazavi SMJ, Sihver L. Digital Screen Time and the Risk of Female Breast Cancer: A Retrospective Matched Case-Control Study. J Biomed Phys Eng. 2024 Apr 1;14(2):169-182. doi: 10.31661/jbpe.v0i0.2310-1678. PMID: 38628888; PMCID: PMC11016821.
- Mortazavi, Seyed Ali Reza et al. “Machine Learning Models for Predicting Breast Cancer Risk in Women Exposed to Blue Light from Digital Screens.” Journal of biomedical physics & engineering vol. 12,6 637-644. 1 Dec. 2022, doi:10.31661/jbpe.v0i0.210
- Mortazavi SAR, Mortazavi SMJ. Women with hereditary breast cancer predispositions should avoid using their smartphones, tablets, and laptops at night. Iran J Basic Med Sci. 2018 Feb;21(2):112-115. doi: 10.22038/IJBMS.2018.27711.6751. PMID: 29456806; PMCID: PMC5811748.
Key Takeaway
While more research is needed to confirm causality, the current body of evidence supports a clear warning—excessive exposure to artificial light at night, particularly blue light from screens, may elevate breast cancer risk.
As digital devices become ever more integrated into our lives, it’s critical to explore preventive strategies, support further interdisciplinary research, and increase public awareness.
Explore more: What has Light got to do with Breast Cancer?