While naps typically help young people retain information they’ve learned, new research suggests that the opposite may be true for those with Down syndrome.

In fact, resting could actually add to memory loss in children with the chromosomal disorder.

That’s according to a study out this week in the Proceedings of the National Academy of Sciences.

Researchers conducted home visits with 24 typically-developing kids and 25 children with Down syndrome. They taught the youngsters a series of made-up words like “tobe,” “wame,” “bope” and “neek” and then assessed how well they retained the new information over varying periods of time. Invented words were used to ensure that they were unfamiliar to all of the children.

The study found that the typically-developing children were most likely to remember the new words when they were evaluated at four hours and 24 hours following the lessons if they took a nap lasting roughly 90 minutes soon after taking in the lessons.

By contrast, those with Down syndrome had much worse retention at the same intervals if they napped.

“In children with Down syndrome, there’s something about having a nap right after learning that seemed to keep them from retaining information as well, which is totally different than what happened in typically developing children, who benefited from that nap,” said Jamie Edgin, an associate professor of psychology at the University of Arizona who worked on the study.

It’s unclear why napping seemed to have a negative influence on the children with Down syndrome, but the researchers said it could reflect difficulty transitioning between various sleep stages. Among those with Down syndrome who were studied, 44 percent did not reach REM sleep during their naps while nearly all of the typically-developing kids did.

“There might be something about getting too little REM sleep and not completing that REM stage that could be related to difficulties with retention,” Edgin said. “There are some recent studies that suggest that people show poorer retention if they get just a little bit of REM than if they get a whole REM cycle. More work needs to be done, but REM sleep is definitely something to consider.”