Spring days are getting longer, yet there’s still a month of school bedtimes to power through. It gets harder to convince the kids to hit the pillow when the sun is still hanging out at 7:30. And it’s not just a stubborn desire to keep playing that poses challenges. Light has a strong physical effect on children’s ability to fall asleep.

According to a recent study at the Sleep and Development Lab at University of Colorado Boulder, bright light at bedtime shuts down melatonin (the sleep-inducing hormone) in preschoolers, ages three to five.

“Although the effects of light are well studied in adults, virtually nothing is known about how evening light exposure affects the physiology, health, and development of preschool-aged children,” says lead study author Lameese Akacem, a CU Boulder instructor and researcher in the lab. “In this study we found that these kids were extremely sensitive to light.”

After one hour of exposure to bright light—about the brightness of a bright room—the kids’ melatonin dropped 88 percent and stayed down for at least 50 minutes after the light was turned off. Researchers suggest that for preschoolers this may not only lead to trouble falling asleep one night, but to chronic problems feeling sleepy at bedtime.

To help reduce the bedtime battles, create a sleep-friendly routine.

Power Down

“The preschool years are a very sensitive time of development during which use of digital media is growing more and more pervasive,” says senior author Monique LeBourgeois, an associate professor in the department of Integrative Physiology. Although the CU Boulder study used a light that was brighter than a typical handheld device in their study with preschoolers, it is still recommended by researchers and the American Academy of Pediatrics (AAP) that all screens be turned off well before kids’ bedtime. Follow the AAP guideline of powering down screens at least 30-minutes before bed, more for preschoolers, and designate kids’ bedrooms as a screen-free zone.

Turn Down

In addition to turning off screens, turn down lights or use a lower wattage light bulb in nightlights. This creates an environment that signals bedtime. Also, be aware of sounds in the house at bedtime. Some children relax from hearing family in the house, while others may suffer from fear of missing out and want to rejoin the activity. Either way, reduce potential background noise to benefit both.

Cool Down

The jury is still out on a perfect sleep temperature, likely because it is different for each individual. It is widely suggested that a slightly cooler room creates a better sleep environment, but being too cold or too hot can also disrupt sleep. Experiment with temperature and styles of pajamas to find the right combination for your child. Whatever the temperature, dress your child in pajamas made of breathable fabric to reduce overheating.

Slow Down

The AAP Brush, Book, Bed program suggests that you do just what it says each night at your child’s bedtime: brush teeth, read a book, and go to bed at a regular time. Predictable routines help children understand and anticipate what comes next, according to the AAP. A soothing soak in the tub before bed can also signal that it’s time to slow down.

Is Your Child Getting Enough Sleep?

How many hours of sleep does your child need? It varies by age. The American Academy of Pediatrics recommends the following amount of sleep each day for optimal health:

  • Infants ages four months to 12 months should sleep 12 to 16 hours (including naps).
  • Children ages one to two years should sleep 11 to 14 hours (including naps).
  • Children ages three to five years should sleep 10 to 13 hours (including naps).
  • Children ages six to 12 years should sleep nine to 12 hours.
  • Teenagers ages 13 to 18 years should sleep eight to 10 hours.

This article was originally published in December 2024.
Deborah Mock

Deborah Mock is the editor for Colorado Parent magazine.