Lights, Melatonin, Babies!

April 30, 2018


How to help your baby prepare to fall—and stay—asleep


The takeaways:

  • Melatonin is a hormone in the brain that promotes sleep.

  • Melatonin release is influenced by the body’s internal clock and the amount of light registered by the eyes.

  • Artificial light exposure suppresses the release of melatonin in the brain, causing wakefulness in babies, children, and adults.

  • Limiting a child’s exposure to artificial light near their bedtime and during the night will result in higher melatonin levels and make falling and staying asleep easier.


Chances are, you or someone you know has used over-the-counter melatonin for help falling asleep. We know melatonin helps promote sleep, but what exactly is it? Where does it come from? And why do some people need to take supplemental doses to fall asleep?


Here’s the scoop: Melatonin is a hormone associated with the onset of sleep in humans and many animals. It’s released from a gland deep in the brain that’s strongly influenced by the body’s internal clock. It’s released in sync with your body’s circadian rhythm, meaning its cycles of high and low levels repeat every 24 hours, which is why you generally feel sleepy at the same times each day. The highest levels of melatonin are, of course, released at night.


But there are other signals that can affect melatonin levels in the body, too—the most powerful one being light. The gland that releases melatonin takes in information about light through the eyes, increasing melatonin levels when it’s dark and suppressing levels when it’s bright. Normally, melatonin increases when it gets dark out making it easier for us to sleep at night. But artificial light, especially from screens, suppresses this release. Which is bad news for anyone trying to get to sleep at night—especially babies and children.


Babies’ and kids’ eyes are more sensitive to light than adults’ are, so their melatonin levels are more strongly affected by light exposure. One study found that children exposed to a bright light before bed showed a 90% reduction in their melatonin levels compared to a different night at the same time without bright light exposure. And most children were still at only 50% of their normal melatonin levels an hour after the initial light exposure. In other words: artificial light is powerful stuff.


In a world where people so often use artificial light and screens well after sunset, it’s not surprising that so many people these days are using supplemental melatonin to fall asleep. Lucky, there are things you can do to help your child—and you!—fall asleep better without having to use over-the-counter melatonin.  


The best thing is, of course, to avoid exposing your baby to too much artificial light—including and especially from screens—after sunset and close to bedtime. Studies have shown that newborn babies who aren’t exposed to any artificial light develop circadian rhythms for melatonin release earlier than children who are exposed to artificial light, and as a result develop a circadian rhythm for sleep earlier. So limiting light exposure doesn’t just help on any given night—it’s a recipe for easier, earlier sleep in the long run.

It’s not a bad idea to consider dimming the lights in the house before bedtime with slightly older children, too. A child who walks into a bright room just before bed will have the same melatonin suppression response and struggle to fall asleep.  


It’s also important to limit light exposure when your baby or child wakes up in the night. Some parents make the mistake of turning on the light during nighttime feedings. But this triggers—you guessed it—melatonin suppression, which will keep them from falling easily back asleep and staying that way.


As you can see, the connection between light, melatonin, and sleep is a strong one. Being mindful of the effects of artificial light on babies and young children will go a long way toward helping them sleep better. Lights out!

Akacem, L. D., Wright, K. P., & LeBourgeois, M. K. (2018). Sensitivity of the circadian system to evening bright light in preschool‐age children. Physiological reports, 6(5).


Klass, Perri. (2018). To help children sleep, go dark.  New York Times.


Mcgraw, K., Hoffmann, R., Harker, C., & Herman, J. (1999). The development of circadian rhythms in a human infant. Sleep, 22(3), 303-10.


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