MONDAY, June 8, 2026 (HealthDay News) — Irregular sleep is linked to lower brain power among preschool kids, a new study says.
Children who don’t stick to a regular sleep schedule tend to have problems with vocabulary and memory, according to research to be presented at an upcoming meeting of the American Academy of Sleep Medicine and the Sleep Research Society. The findings were published recently in the journal Sleep.
“Children with more irregular sleep patterns tended to perform worse on verbal and memory tasks, even after accounting for total sleep time,” said lead researcher Karolina Rusin, a graduate student at the University of Massachusetts Amherst.
“These findings reinforce growing evidence that sleep regularity, not just duration, plays an important role in healthy child development,” Rusin said in a news release.
For the new study, researchers assessed the sleep of 379 preschool kids with an average age of 4. The team also tested children’s vocabulary, memory, planning and thinking skills using cognitive tests.
Here's what researchers found:
Overall, children’s sleep duration varied by nearly an hour on average, and their sleep midpoint varied by about 32 minutes.
Fluctuations in sleep duration and sleep midpoint were linked to lower vocabulary scores.
Likewise, fluctuations in sleep midpoint and alignment of sleep to a child’s daily schedule were associated with lower performance on memory tests.
However, thinking and planning skills – also known as executive function – were not affected by variable sleep.
“Children’s executive attention was not related to sleep variability measures in this sample, which suggests that not all cognitive outcomes are equally affected by irregular sleep,” Rusin said. “Further research is needed to understand the relationship between sleep variability and cognitive health across age groups and demographics.”
The researchers are scheduled to present their findings June 15 at the SLEEP meeting, which takes place in Baltimore.
More information
The Nemours Foundation has more on preschoolers and sleep.
SOURCE: American Academy of Sleep Medicine, news release, June 4, 2026