Potential Link Between Anxiety and Insomnia in Individuals with Autism Spectrum Disorders

Background:  One of the most common co-occurring medical conditions in individuals with ASD is chronic, severe insomnia, with a prevalence estimate of 60-80% (Wiggs & Stores, 2004; Souders et al., 2009). One hypothesis for elevated insomnia in ASD is hyper-arousal, which may be related to altered levels of excitatory neurotransmitters (Bourgeon, 2007). Hyper-arousal is also a key component of many anxiety disorders, and more than half of children with ASD experience clinically significant problems with anxiety (Sukhodolsky et al., 2008).  Although it appears likely that hyper-arousal, anxiety and insomnia are related in ASD, we presently have only a limited understanding of this relationship.

Objectives:  The purpose of this study was to investigate the nature of the relationship between anxiety symptoms, biomarkers of arousal dysregulation and sleep parameters in children and adolescents with ASD as compared to typically developing controls (TDC).

Methods:  Sixty individuals with ASD, ages 6-17, were compared to 16 TDC. Participants had their ASD diagnosis confirmed by ADOS/ADI. Anxiety symptoms were evaluated via the Anxiety Disorders Interview Schedule (ADIS-C/P, a two-hour child and parent clinician administered interview), and multiple parent-administered anxiety questionnaires. Sleep was characterized by 5-7 nights of actigraphy (a micro-computer that measures movement), sleep diaries, sleep questionnaire and a comprehensive medical interview. Diurnal urine samples were obtained the evening and night prior to the center evaluation, in order to measure catecholamine levels (an index of arousal).  The evaluation also included measures of heart rate, respiration, skin conductance and temperature with the Biopac MP150 and BioHarness.

Results:  The current, first phase of the analysis included summary statistics and cross-tabulations, followed by a Fisher’s Exact test.  A DSM-IV-TR anxiety diagnosis was identified with the ADIS-C/P in 28/58 of the ASD subjects (48%).  One of the 16 TDC participants was identified with a specific phobia.  53% of the ASD subjects had an insomnia diagnosis based on sleep diaries, actigraphy, questionnaires and history. Two of the 16 TDC had insomnia (12.5%). We found a significant association (p < 0.0001) between Anxiety Diagnosis and an Insomnia Diagnosis in individuals with ASD (25/28). Only 6 individuals with ASD without anxiety had insomnia (6/30). In the second phase of the analysis we will be correlating anxiety questionnaires and sleep measures. We will also be analyzing the urine samples for norepinephrine, epinephrine, cortisol and melatonin levels.

Conclusions:  This preliminary analysis suggests that anxiety and insomnia are closely linked. We expect that after the completion of the analysis we will have greater insights into the relationship between arousal dysregulation, anxiety, and insomnia in ASD.  This understanding will ultimately lead to more targeted co-treatment of anxiety and insomnia in ASD.