Let’s work with organizations to reduce light pollution

Dear Editor:

The night sky over North America has been growing brighter by about 10% each year. The DMV, including Loudoun, is the most light-polluted region of the country, with more than 200,000 times the artificial light of America’s naturally dark night skies.  Scientists predict that in 20 years, no stars will be visible here at night. 

Light pollution results in the loss of contrast between light and dark, day and night, which confuses our circadian rhythm and jeopardizes our health. Humans have an internal master clock, the hypothalamus of the brain, which is synced to this 24-hour light cycle. 

Our eyes have photoreceptors that send light information to the brain. Every normal body function from hormone secretion to cell division depends on the control of the hypothalamus. Exposure to light at night disrupts this natural control of our physiology.

Research links light pollution to a range of health problems including: cancer, heart disease, diabetes, and Alzheimer’s disease.  Specifically, researchers have used satellite data to measure light pollution at residential addresses of many thousands of people worldwide. 

These studies show that people living in places with the worst light pollution have a 31% higher risk of high blood pressure, 29% higher risk of death from coronary heart disease, 28% higher risk of diabetes, 17% higher risk of cerebrovascular disease [strokes and brain aneurysm], and 12% higher risk of breast cancer. 

Multiple studies have also shown the association between disrupted circadian rhythm and increased risk of aggressive prostate cancer.  And this risk remains, even after studies control for the presence of air and noise pollution.

This is an avoidable problem.  Locales across the globe have worked with the nonprofit DarkSky International and similar organizations to develop common sense legislation and voluntary programs to reduce light pollution – Loudoun should be one of them.

SJ Anderson, MD, PhD

Leesburg