Sleep concerns are common in children with autism spectrum disorders (ASD). We identified objective sleep measures that differentiated ASD children with and without parental sleep concerns, and related parental concerns and objective measures to aspects of daytime behavior. ASD poor sleepers differed from ASD good sleepers on actigraphic (sleep latency, sleep efficiency, fragmentation) and polysomnographic (sleep latency) measures, and were reported to have more inattention, hyperactivity, and restricted/repetitive behaviors. Fragmentation was correlated with more restricted/repetitive behaviors. This work provides the foundation for focused studies of pathophysiology and targeted interventions to improve sleep in this population.