Can Night Light Give You Cancer?

In 2006, a jaw-dropping study was published that linked nighttime light to some forms of cancer. Can light really give you cancer? Let's find out what's actually going on here.

What Melatonin Is

Melatonin is a chemical made in the pineal gland. Melatonin, which is also found in plants, animals and even fungi, is heavily influenced by the light/dark cycle and is strongly linked to sleep regulation. In fact, melatonin is sometimes referred to as the "darkness hormone" because proper production of melatonin is vital to sleep.

But melatonin is also strongly linked to what some people refer to as your "biological clock". If you've ever experienced jet lag after an overseas flight or suddenly switched from the day shift to the night shift at work, you know all too well the importance of your internal timekeeper.

The Melatonin Hypothesis

In any 24-hour period, your body experiences a set of fairly regular physiological processes. Scientists refer this sequence of bodily activities as your circadian rhythm and now know that your circadian rhythm is heavily affected by your body's production of melatonin.

Recognition of the circadian rhythm is nothing new. The ancient Greeks wrote about it and 17th century botanists experimented with it in plant studies. But recently the effect of nighttime light on the circadian rhythm has been linked to hormone-dependent diseases like breast cancer. This discovery, called the melatonin hypothesis, suggests that being exposure to light (either natural or artificial) in the evening and nighttime hours disrupts melatonin production to such a degree that cancer cells are allowed to flourish.

How Melatonin and Light are Linked to Cancer

Melatonin regulates your sleep but it also influences the natural activity in your cells. You can think of melatonin not only as a sleep aid for you; melatonin also acts a bit like a sleep aid for cancer cells. Without the proper levels of melatonin to signal them to "rest", those cancerous cells continue to grow and divide around the clock.

If this sounds a bit far-fetched, it shouldn't. Study after study has demonstrated that people who work overnight hours have higher rates of hormone-related diseases like cancer.

Should You Worry about Melatonin and Cancer?

Only your doctor can evaluate your risk of cancer. If you have any questions about the melatonin hypothesis and how it might affect your risk of hormone-dependent cancers like breast cancer, talk to a qualified health care provider for the information that's appropriate for you.

References:

Ravindra, T., Lakshmi, N., Ahuja, Y. (2006). Melatonin in pathogenesis and therapy of cancer.

Pandi-Perumal, S., Srinivasan, V., Maestroni, G., Cardinali, D., Poeggeler, B., Hardeland, R. (2006). Melatonin: Nature's most versatile biological signal?

Davis, S., Mirick, D. (2006). Circadian disruption, shift work and the risk of cancer: a summary of the evidence and studies in Seattle.