American Academy of Sleep Medicine Jun 4 2026 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