Assessing a hyperarousal hypothesis of insomnia in adults with autism spectrum disorder.
Adults with autism and insomnia show high bedtime body arousal plus a blunted evening cortisol dip, pointing to a hyper-aroused yet exhausted stress system.
01Research in Context
What this study did
Greene et al. (2019) asked adults with autism who complain of insomnia to spend one night in a sleep lab.
Before bedtime the team sampled saliva for cortisol and checked heart rate and body tension.
They also noted who took no medicines to see if drug use changed the numbers.
What they found
People who said they could not sleep well had higher cortisol and a faster heartbeat before lights-out.
Adults who took no nightly medicines had even lower evening cortisol, a sign the stress system is stuck on low.
The results support the idea that too much body arousal, plus a tired stress axis, feeds insomnia in autism.
How this fits with other research
Curin et al. (2003) first saw low cortisol in autistic people years earlier. K et al. now link that same low evening cortisol to poor sleep, showing the old finding matters at bedtime.
Bravo Balsa et al. (2024) studied teens and young adults and found more total daily cortisol, not less. The gap looks like a contradiction, but Laura measured 24-hour output while K et al. looked only at the bedtime drop—different windows, different story.
Ferraiolo et al. (2026) used surveys and found bad sleep efficiency predicts depression. K et al. add a body reason—high presleep arousal—so you now have both a mood marker and a biomarker to watch.
Why it matters
You can now screen adult clients for insomnia by asking about bedtime tension and, when possible, check a single evening cortisol sample. If arousal is high and cortisol flat, teach paced breathing, dim lights, and consider melatonin before reaching for stronger sleep drugs.
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02At a glance
03Original abstract
This study aimed to investigate the relationship between sleep, psychopathology (anxiety, depression and presleep arousal) symptoms, and cortisol in adults with autism spectrum disorder (ASD). The sample composed of 29 adults with ASD (51.7% males) and 29 control adults (51.7% males) aged 21-44 years. Thirteen adults with ASD were medicated for a comorbid diagnosis of anxiety and/or depression (ASD-Med), while the remaining 16 adults with ASD were not medicated for such diagnoses (ASD-Only). Participants completed a questionnaire battery, 14-day sleep/wake diary and 14-day actigraphy assessment. On one day during the data collection period, participants collected five saliva samples, hourly, prior to sleep and two morning samples; immediately upon waking and 30 min thereafter for the analysis of cortisol. Cortisol 1 hr prior to habitual sleep onset time was associated with poorer sleep efficiency in both ASD groups and increased wake after sleep onset duration (ASD-Only). Higher subjective somatic arousal was also associated with increased sleep onset latency, regardless of group, and poorer sleep efficiency in the ASD-Only group. ASD-Only participants had significantly greater reductions in evening cortisol concentrations compared to both ASD-Med and control participants. No significant group differences were found for the cortisol awakening response. Findings suggest a hyperarousal hypothesis of insomnia in adults with ASD. Moreover, the low cortisol levels observed in ASD-Only adults suggest dysregulation of the hypothalamic-pituitary-adrenal (HPA) axis. Longitudinal studies exploring the interplay between insomnia, anxiety and HPA axis regulation across the lifespan in those with ASD are warranted. Autism Res 2019, 12: 897-910. © 2019 International Society for Autism Research, Wiley Periodicals, Inc. LAY SUMMARY: Both objective (cortisol) and subjective (somatic) physiological arousal were associated with poor sleep quality in adults on the autism spectrum. Adults with autism spectrum disorder (ASD) who were not medicated for a comorbid diagnosis of anxiety and/or depression also had dampened cortisol secretion, suggesting a dysregulation of the hypothalamic pituitary axis. Longitudinal studies investigating the relationship between sleep, psychopathology symptoms and physiological arousal in autistic individuals are warranted. Autism Res 2019. © 2019 International Society for Autism Research, Wiley Periodicals, Inc.
Autism research : official journal of the International Society for Autism Research, 2019 · doi:10.1002/aur.2094