Nighttime Lights Threaten Human Health

By Brad Hopkins and Chris Clark

[from the Commercial Record, April 14, 2022]

Light pollution has a negative effect on human health. It interrupts our 24-hour clock and causes sleep disorders as well as other health issues. 

The human day/night cycle, known as the circadian clock, affects how our bodies work. Among other things it affects brain wave patterns and the production of melatonin. Interrupting this natural rhythm can cause sleeplessness, depression, cancer, and heart disease. In 2012,  the American Medical Association recognized that artificial light at night may cause some types of cancer and is a general health risk. 

Melatonin is made by the body and released during periods of darkness. It serves several purposes, but primarily controls the daily cycles within our body. Artificial light at night can interrupt the release of melatonin. Reducing the amount of light can help you keep a normal melatonin rhythm. Short wavelengths of light – the blue portion of the spectrum – are the primary culprits affecting melatonin levels. That’s a great reason to use “warm” light bulbs.

Extending our waking hours by using artificial light also throws off the internal clock. This particularly affects night shift workers. According to the National Institute of Health (NIH), interrupting the circadian rhythm affects our ability to go to sleep and wake up at regular times. It can also lead to decreases in decision-making ability, understanding new information, and learning. A recent study in Spain showed that cancer risk is connected to increased exposure to artificial light at night; women had 1.5 times higher risk of developing breast cancer and men had 2 times higher risk of developing prostate cancer. 

The NIH believes people function best when they sleep at night and act in the daytime. If outdoor light is shining into your window and disrupting your sleep, find a way to block that light. A good night’s sleep can help decrease weight gain, stress, and depression.

Dark Sky Action Item 5: Do you like to read books after dark? Make sure that the light bulb you’re using has a warm temperature rating (300K or less).

Next week: “Ineffective Lighting is Wasteful”

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