A new study reveals that irregular sleep patterns — such as variable bedtimes and inconsistent sleep duration — are linked to lower scores in receptive vocabulary and visuospatial memory among preschool-age children, even when total sleep time is accounted for.
The Research
Presented at the SLEEP 2026 annual meeting on June 15, researchers from the University of Massachusetts Amherst analyzed sleep and cognitive data from 379 preschool children (average age 4.3 years). Sleep was tracked using actigraphy wearables, measuring variability in sleep midpoint (the halfway point between bedtime and wake time), sleep duration, and social jet lag (the discrepancy between weekday and weekend sleep schedules).
Cognitive assessments included the Peabody Picture Vocabulary Test for receptive vocabulary (n=322), a memory grid task for visuospatial memory (n=62), and a preschool-adapted flanker task for executive attention (n=60). Results showed that greater variability in sleep midpoint, sleep duration, and higher social jet lag were each associated with lower vocabulary scores. Visuospatial memory was specifically linked to variability in sleep midpoint and social jet lag, but not to duration variability. Surprisingly, executive attention showed no significant association with any sleep regularity measure.
On average, children’s sleep duration varied by about 60 minutes, and sleep midpoint shifted about 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.
Why It Matters
This study underscores that sleep regularity — not just total hours — is a critical, independent factor for healthy brain development. The findings are especially relevant for parents and educators, as the cognitive domains affected (vocabulary and visuospatial memory) are foundational for language learning and spatial reasoning. The discovery that executive attention was unaffected suggests that irregular sleep selectively impairs certain cognitive functions rather than causing a broad deficit.
What You Can Do
To protect your child’s cognitive development, aim for consistent bedtimes and wake times seven days a week. Minimize social jet lag by keeping weekend schedules close to weekday routines. For adults, the same principle applies: prioritize a regular sleep schedule to support memory and learning.
Source: Neuroscience News
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