Lights at night lower your melatonin and affect your circadian rhythm, which can hurt your fertility, according to a new study
Using your phone as a nightlight or your TV to soothe you to sleep? You should stop—pronto. Not only does it ruin your quality of sleep and leave you with dark circles no amount of concealer can cover, but a new study shows that light at night can actually increase your risk of infertility.
Researchers from UCLA, Osaka University, and the Japan Science and Technology Agency looked at how exposure to artificial light at night affects the fertility of female mice and found that not only did darkness matter, but so did the age of the mice. When exposed to traditional day-night light patterns, older mice approaching rodent menopause (yes, that's a thing) were able to get pregnant 71 percent of the time. But when they were exposed to artificial light at night, that number dropped to 10 percent. The light variation disrupted the fertility of younger mice as well, but not nearly as drastically. (These Affordable Products Can Help You Have a Better Night's Sleep.)
So what do light at night and fertility have to do with each other? The connection has to do with your body's circadian rhythm, that "internal clock" which controls a variety of biological functions including your menstrual cycle. Sleep in general has been shown to improve fertility in both women and men, but this study shows that melatonin—the hormone that helps regulates your sleep cycle—is a crucial factor to that improvement.
Melatonin is produced by the pineal gland, which is located in the brain near your vision centers. When your eyes see waning light or darkness, the pineal gland assumes nighttime is coming and kicks up production of the hormone, with levels peaking right before you fall asleep. Melatonin, in addition to making us sleepy, also modulates estrogen and progesterone receptors, the two main hormones that influence your fertility. Too much light at night from indoor lights, TVs, or digital screens slows the production of melatonin just when it should be at its highest, inducing insomnia and messing up your female reproductive hormones, the study explains. (Try these 3 Ways to Use Tech at Night—and Still Sleep Soundly.)
And while the study was done on mice, the scientists believe the findings may apply to human females as well—especially those over the age of 30, as their fertility levels are naturally starting to decline.
If you're in the habit of falling asleep with your phone on your pillow, don't fret. The researchers found that the ill effects on fertility were easily reversed by establishing a consistent night schedule. (Want more? Here are 13 Expert-Approved Sleep Tips.) If you've been trying for awhile to have a baby, cleaning up your "circadian hygiene" could be immensely helpful, said Gene Block, Ph.D., CEO of the University of California Los Angeles and co-author of the study. He advises steps like turning off all electronics at least an hour before bed, setting regular meal times, and avoiding rotating shiftwork or schedules that lead to irregular sleep. And when it comes to exactly how much shut-eye is necessary for optimal baby-making, an earlier study out of Korea says the sweet spot is seven to eight hours per night. And that you can get started on tonight.