Ever wonder how artificial light may impact your health? A large study in Spain looked into how nighttime exposure to artificial light (ALAN) might link to hormone-dependent cancers like breast and prostate cancer.
Methods:
They studied 1,219 breast cancer cases, 1,385 female controls, 623 prostate cancer cases, and 879 male controls.
Measuring Artificial Light Exposure: They used questionnaires for indoor light and images from the International Space Station for outdoor light in Barcelona and Madrid.
Chronotype Check: They also checked people’s chronotype (are you a morning person or a night owl?) to see if it affected adaptation to light at night.
Key Findings
Outdoor Blue Light & Cancer: High exposure to outdoor blue light was linked to higher risks of breast cancer (47% increase) and prostate cancer (105% increase).
Sleeping in Darkness: Men sleeping in well-lit rooms had a nearly 3 times higher risk of prostate cancer, while women sleeping in well-lit rooms had a slightly lower risk of breast cancer.
Overall Light Intensity: Interestingly, higher overall light intensity outdoors was more common among controls than cancer cases, especially for prostate cancer.
Takeaway
Blue Light Alert: Blue light at night seems particularly risky for hormone-dependent cancers.
Sleep Dark: Men, especially, might want to sleep in total darkness. This has also been shown to boost sleep quality overall.