LAUSR

ABSTRACT Sleep disturbances are the comorbid conditions most frequently associated with autism spectrum disorder (ASD). Sleep problems might precede and worsen the behavioral outcomes of ASD. This study examined the association between sleep habits/problems and autistic traits in toddlers. Eighteen-month-old toddlers (N = 426; boys/girls, 204/222) were assessed for autistic traits using the Japanese version of the Modified Checklist for Autism in Toddlers and sleep habits/problems using the Child and Adolescent Sleep Checklist during health checkups. There were no significant differences in sleep habits, including total sleep time, wake time, bedtime, and naps, between autistic toddlers (n= 26) and non-autistic toddlers (n= 400). However, toddlers with autistic traits more commonly exhibited bedtime resistance, abnormality in circadian rhythm, and sleepiness outside of naptime than toddlers without autistic traits. Moreover, autistic traits were significantly associated with daytime sleepiness. Autistic traits are associated with sleep problems in toddlers. In particular, daytime sleepiness might be avisible symptom that enables the earlier detection of ASD in children.