DARIEN, IL – A new study to be presented at the SLEEP 2026 annual meeting found that irregular sleep — including variability in sleep timing and duration — was associated with lower receptive vocabulary and visuospatial memory scores in preschool-age children, even after accounting for total sleep duration.
Results show that greater variability in sleep midpoint was associated with lower receptive vocabulary scores, as were greater variability in sleep duration and higher social jet lag. Visuospatial memory performance was associated with variability in sleep midpoint and social jet lag, but not with variability in sleep duration. Executive attention was not significantly associated with any measure of sleep variability. On average, children's sleep duration varied by approximately 60 minutes, and sleep midpoint varied by approximately 32 minutes across the assessment period.
"Children with more irregular sleep patterns tended to perform worse on verbal and memory tasks, even after accounting for total sleep time," said lead author 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."
According to the American Academy of Sleep Medicine, sleep is essential to health, and it requires adequate duration, good quality, appropriate timing and regularity, and the absence of sleep disturbances or disorders. The AASM recommends that preschool-age children 3-5 years old sleep 10-13 hours on a regular basis to promote optimal health.
The study involved 379 preschool-age children with a mean age of 4.3 years. Sleep was assessed using actigraphy-derived measures of regularity, including individual standard deviation of sleep midpoint, individual standard deviation of sleep duration, and social jet lag. Cognitive outcomes were assessed across three tasks: receptive vocabulary using the Peabody Picture Vocabulary Test (n=322), visuospatial memory using a memory grid task (n=62), and executive attention using a preschool-adapted flanker task (n=60).
Rusin noted that the finding regarding executive attention was unexpected and points to an important nuance in how sleep regularity relates to different cognitive domains.
"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."
This study was supported by a grant from the National Institutes of Health. The research abstract was published recently in an online supplement of the journal Sleep and will be presented June 15 during SLEEP 2026 in Baltimore. SLEEP is the annual meeting of the Associated Professional Sleep Societies, a joint venture of the American Academy of Sleep Medicine and the Sleep Research Society.
