Researchers found that preschoolers who spend more time watching television, playing video games or using computers—especially if they’re sneaky at bedtime—get less sleep, reports Medical Xpress.

Increased media use is linked to a shorter night sleep and a longer daytime nap for preschoolers, according to a new study by Jessica Moorman and Kristen Harrison of the U-M Department of Communication Studies.

Previous research indicates that children aged 2-5 should only use screen media for about one hour a day to ensure their healthy growth and development. This guideline, however, is rarely followed. In the current study, daily screen time for preschoolers was more than double this recommendation.