Original ResearchPublished 19 August 2026Exploring nightly variability in sleep apnea and changes in severity classification with multi night sleep testing in a population based cohort of young childrenSolveig Magnusdottir · Ingibjorg Ingolfsdottir · Hugi Hilmisson · Laufey Hrolfsdottir · Magnus Birkisson · Erla Hallgrimsdottir · Groa Johannesdottir · Hannes PetersenFrontiers in Sleepdoi 10.3389/frsle.2026.1903809