Sleep is often linked to improved memory retention and learning; however, a recent study funded in part by the Jerome Lejeune Foundation suggests that this might not be the case for children with Down syndrome.
The study conducted at the University of Arizona included 25 children with Down syndrome and 24 without. The children were taught the meanings of new nonsense words, such as “tobe,” “wame,” “bope” and “neek,” to ensure that they were words none of them had known. The results were surprising:
Over the course of several home visits, the researchers tested the children’s retention of the new words at varying intervals: five minutes after they’d learned the words; four hours after they’d learned the words and stayed awake; four hours after they’d learned the words and taken a nap shortly after learning them; and 24 hours later to test for long-term retention.
The typically developing children retained the new words better four hours and 24 hours after learning them if they took an approximately 90-minute nap shortly after the learning took place. If the children with Down syndrome napped after learning the words, retention was much worse at the four-hour and 24-hour intervals than if they didn’t nap.
Jamie Edgin, UA associate professor of psychology and senior author of the PNAS paper summarized:
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 benefitted from that nap.
The researchers believe that the difference may be tied to REM sleep. Studies show the REM sleep is tied to memory consolidation. However, individuals with Down syndrome struggle with sleep disorders such as sleep apnea and difficulty transitioning between sleep stages. Although further research may be needed to support the theory, 44 percent of the children with Down syndrome in the study did not enter into REM sleep during their naps, while only about 6 percent of typically developing children failed to get to REM sleep.
More research would also be needed to determine whether the physical benefits of naps might outweigh the negative cognitive effects. Meanwhile, the researchers are working on an additional project to determine whether limiting naps can improve learning for children with Down syndrome.
This is not new territory for the Jerome Lejeune Foundation, as the Jerome Lejeune Institute in France has sponsored ongoing clinical trials and studies regarding sleep apnea and early detection and treatment of respiratory sleep disorders in children with Down syndrome.