Early sleep problems predict repetitive behaviors later in childhood. And toddlers who overreact or underreact to sensory stimuli have more repetitive behaviors and other autism traits later on.
Together, the findings from two independent studies suggest that early behavioral differences may set the stage for restricted and repetitive behaviors, a core characteristic of autism also associated with other conditions of brain development.
The studies also highlight areas for early intervention, particularly if further research identifies causal links between these traits.
Autistic children are twice as likely to have trouble sleeping as typical children. Their poor sleep has been linked to severe traits including severe repetitive and restricted behaviors.
Children with sleep problems at age 4 later exhibit more higher-order repetitive behaviors than do their peers without sleep problems. They also experience a more rapid increase in these behaviors between ages 2 and 4. The work appeared in March in the Journal of Autism and Developmental Disorders.
The study shows an association between sleep and the repetitive behaviors, says Brian Boyd, associate professor of applied behavioral science at the University of Kansas, who was not involved with either study. But it is unclear whether sleep problems lead to the behaviors or the other way around — or whether an underlying factor contributes to both, he says.