More than half of children with Autism Spectrum Disorder (ASD) also experience clinically significant problems with anxiety (Sukhodolsky et al., 2008). New research conducted at the Center for Autism Research (CAR) at The Children’s Hospital of Philadelphia and the University of Pennsylvania (UPENN), School of Nursing suggests that ASD which co-occurs with anxiety can have another harmful consequence: insomnia. Insomnia is defined by difficulties falling and/or staying asleep with impairments in daytime behavior. In a recent study, CAR researchers including Dr. Margaret C. Souders found that children with ASD who received an additional diagnosis of an anxiety disorder were significantly more likely to have insomnia as compared to children with ASD without a diagnosis of anxiety. This preliminary data also showed that there were no significant differences between typically developing children’s sleep latency and night waking, compared to children with ASD without an additional diagnosis of anxiety. Anxiety in this study was diagnosed by a team of CAR psychologists using the gold standard tool for anxiety the Anxiety Disorders Interview Schedule (DSM-IV) – Child/Parent (ADIS-C/P) (Silverman & Albano, 2007).
Adequate sleep is critical for the most advantageous neurobehavioral and physiological development and functioning (Banks and Dinges, 2007, Goel, et al 2009). Poor sleep has been shown to have harmful effects on cognition, behavior, mood, and attention (Gozal, 1998, Maquet, 2001). The prevalence of sleep problems in children with ASD is 60-80%, two to three times the rate of typically developing children (Souders, et al, 2009). There are many possible causes for sleep disturbances in ASD. Researchers think that the core deficits of ASD and their underlying neurobiology may predispose children with ASD to having sleep problems (Souders, et al, 2009). The two predominant sleep disorders identified in children with ASD are Behavioral Insomnia of Childhood (an insomnia caused by external factors) and Insomnia Secondary to their Pervasive Developmental Disorder (PDD) (an insomnia caused by internal factors) (Wiggs and Stores, 2004, Souders, et al, 2009). Insomnia due to a child’s ASD would be diagnosed when robust behavioral techniques are used by the family, behavioral insomnia is ruled out, and no identifiable medical condition is disrupting sleep. This sleep problem is best described as insomnia due to PDD (Diagnostic Code 327.15) (Souders, 2009).
One of the main emerging hypotheses for insomnia caused by internal factors in ASD is synaptic pathway abnormalities. Scientists think that anomalies in the excitatory neurotransmitters in the synaptic pathways of the brain may account for “arousal dysregulation” in individuals with ASD. This means that an individual’s brain and neurological system does not sufficiently and consistently regulate or control the internal levels of anxiety, fears and sensitivity thresholds to environmental stimuli (for example, sounds, clothes, tastes and smells) experienced by children with ASD. Arousal dysregulation may be contributing to difficulties in initiating and maintaining sleep and daytime behavior. Arousal dysregulation in children with ASD may produce a constellation of behavioral symptoms including anxiety, sensitivities to sensory stimuli, in-attention and insomnia.
This recent study explored the relationship between anxiety (a part of the arousal continuum) and sleep problems in ASD. The CAR researchers conducted an in-depth assessment of anxiety using anxiety questionnaires and the ADIS-C/P. Sleep was characterized by seven nights of actigraphy (a micro-computer worn at night during sleep to monitor movements), sleep diaries, sleep questionnaires, and a comprehensive medical interview by Dr. Souders, an assistant professor and pediatric nurse practitioner.
To date, (new data is still being analyzed), thirty-five individuals, ages 6-17, have been compared to eight individuals with typical development. Fifty-one percent of the individuals with ASD were diagnosed with an anxiety disorder. One of the typically developing individuals had a specific phobia. Insomnia was identified in 54% of the children and adolescents with ASD. No individuals with typical development had insomnia. However, four children with ASD had medical conditions causing insomnia. One child had severe allergies and one child had nocturnal reflux that resulted in frequent coughing at night. They were referred to their primary physician. One child had symptoms of obstructive sleep apnea and one child had symptoms of restless leg syndrome. They were referred to a sleep center. These cases were removed from the analysis. The first phase of the preliminary analysis included summary statistics and cross-tabulations, followed by a formal statistical assessment using Fisher’s Exact test. We found a significant association between anxiety (Anxiety Diagnosis and No-Anxiety Diagnosis) and insomnia in individuals with ASD. The second phase included Pearson correlations between anxiety and the continuous sleep variables. Sleep latency (the time it takes to fall asleep), sleep efficiency (the amount of time in bed asleep over the time in bed) and wake in minutes were all significant. These preliminary results suggest that anxiety and insomnia in ASD are linked. The clinical conduct of this study is complete and we are in the process of doing a full analysis. These findings may have important implications for treatment of sleep problems and anxiety symptoms in individuals with ASD.
Our next steps are to explore an innovative treatment for individuals with ASD and anxiety and insomnia. Based on the idea that a subset of individuals with ASD has anxiety and a hyper-aroused state, we developed a Tailored Behavioral Intervention that addresses the internal and external factors that threaten sleep. The Tailored Behavioral Intervention includes positive routines, calming module (developed to decrease arousal levels) and faded bedtime protocol. The Tailored Behavioral Intervention is novel in that it includes a detailed calming module with 12 soothing and relaxing activities to choose from in order to help an individual fall asleep. If the Tailored Behavioral Intervention is effective and acceptable to caregivers and individuals with ASD, we hope it will be incorporated into the Sleep Tool Kit available to families from the Autism Treatment Network (http://www.autismspeaks.org/science/resources-programs/autism-treatment-network/tools-you-can-use/sleep-tool-kit). The Sleep Tool Kit developed by Dr. Beth Malow and colleagues from Vanderbilt University provides sleep education and behavioral strategies to improve sleep in children with ASD with external sleep problems. Our future research will continue to focus on internal factors related to insomnia in individuals with ASD, namely anxiety and arousal dysregulation.