Sleep in Young Children With Autism, <scp>ADHD</scp> and Combined Presentations

Autism and attention deficit hyperactivity disorder (ADHD) are often accompanied by sleep problems. Longitudinal studies hint towards a greater proportion of persisting sleep problems across early development in neurodivergent compared to neurotypical individuals. Within the context of a prospective infant sibling study of autism and ADHD (n = 209), we compared early caregiver-rated sleep trajectories of individuals diagnosed with autism, ADHD or cooccurring autism and ADHD (AuDHD) at 36 months with two groups that did not meet diagnostic criteria-one group of individuals with and one without elevated likelihood of autism and/or ADHD. Sleep behaviors assessed at 10 and 14 months (i.e., number of night awakenings and settle durations) did not differ between individuals with and without a diagnosis of autism and/or ADHD. At 24 and 36 months, individuals diagnosed with autism and/or ADHD took longer to fall asleep, had less sufficient sleep, more parasomnia-related behaviors and had greater overall sleep disturbance than those without a diagnosis, suggesting that their sleep problems are more circumscribed than often reported for older age ranges. In autism specifically, bedtime resistance improved from 24 to 36 months. While additional studies incorporating objective sleep measures are needed, the current results indicate that sleep involvement in neurodevelopmental conditions may mainly reflect transdiagnostic rather than diagnosis-specific processes in early childhood.