Rethinking bedtime resistance in children with autism: is restless legs syndrome to blame?

In this study we investigated the clinical correlates of restless legs syndrome in children with autism and report on our experiences with response to treatment. A retrospective chart review of children seen in our sleep center from 2016-2019 was performed to identify children with autism and chronic insomnia. Patients underwent clinical assessments for restless legs symptomatology. Overnight polysomnogram, serum ferritin testing, and response to clinical treatment data were collected. A total of 103 children with autism and chronic insomnia were identified (age range 2-19 years). Of these, 41 children (39%) were diagnosed with restless legs syndrome. The diagnosis of restless legs syndrome was associated with significantly lower serum ferritin levels (mean 29 ± 18.62 ng/mL vs non-restless legs syndrome 56.7 ± 17.59, P < .001) and higher periodic limb movements of sleep on polysomnogram (8.12 ± 6.6 vs non-restless legs syndrome 0.06 ± 0.17). The presence of leg kicking, body rocking, or any symptoms involving the legs was highly correlated with the diagnosis of restless legs syndrome. Positive treatment response was noted in nearly all treated patients, including those treated with oral iron supplementation alone (25 children, 23 responders), gabapentin alone (12 children, all responders), and combination therapy (3 children, all responders). Our findings suggest restless legs syndrome may represent an under-recognized cause of insomnia in children with autism. Initial assessment should include a thorough query of behaviors related to nocturnal motor complaints, because restless legs syndrome may be a treatable cause of sleep disruption.