Do you sleep in darkness or use a night light? Find out why sleeping with a night light could be hazardous to your health.
Do you feel more secure when you leave on a night light? It may be comforting to have some light in the room, but sleeping with light shining at night could be harmful to your health. How? By altering natural circadian rhythms that regulate bodily functions and help to keep cancer cells in check.
Why You Shouldn’t Use a Night Light
Researchers exposed two groups of mice to periods of light and darkness. One group of mice received twelve hours of daylight and twelve hours of darkness. The other group was exposed to twelve hours of light, but one hour of darkness was replaced with an hour of light. The results? That single hour of light, at a time the mice would normally have been in darkness, led to changes in cell division and gene expression that could increase the risk of cancer.
It’s not just mice that may suffer the health effects of light at night. Studies show that women who are exposed to light at night, by working night shifts or living in neighborhoods with lots of street lights, have a higher risk of breast cancer. This raises the concern that exposure to light at night could play a significant role in a variety of human cancers.
Why Is It Important to Sleep in Darkness?
At night, the body produces melatonin, a hormone secreted by the tiny pineal gland located in the brain that helps to regulate the sleep-wake cycle. Melatonin production is shut down when a person is exposed to light at night – even in small amounts. Melatonin plays an important role in suppressing cancerous tumor formation by stopping their replication and ability to grow. It does this by blocking the action of a fatty acid called linoleic acid, a fatty acid needed for tumor growth.
Melatonin production may suppress a variety of different types of tumors including breast and colon cancers – and a night light interferes with the production of the melatonin needed to keep these tumor cells in check.
Should You Use a Night Light?: The Bottom Line
Unless you’re terrified by the dark or at an increased risk of falling, it’s a good idea to cut off the night light and sleep in complete darkness. Even small amounts of light from cell phones, computers, and alarm clocks can shut down melatonin production. Do your health a favor and switch off the night light – for good.
Journal of the National Cancer Institute online. “Light at Night, Shiftwork, and Breast Cancer Risk”
On Fitness. July/August 2010. page 10.