Health Risks Linked to Leaving Lights on at Night

Light at night can disrupt sleep patterns and contribute to obesity, diabetes, and more

Exposure to light leads to advances or delays in your circadian rhythm, known as phase shifts. Shutterstock

Ensuring your bedroom is pitch black at night—without light exposure from a television, window, cellphone, or even your alarm clock—is a simple way to reduce your risk of chronic disease. It was only about 130 years ago that electric light was invented, bringing with it drastic changes in the way humans function on a daily basis.

Now that we’re able to work, eat, and play well after the sun sets, artificial lighting has had immense benefits for us, but our endogenous circadian clocks haven’t fully adjusted. The fact is, exposure to unnatural electric light, including light at night (LAN), disrupts sleep and many other biological processes.