Emma Baker, Murdoch Children’s Research Institute, OTARC Alumni, on the types and causes of sleep problems in adults with autism
Much research has been done on sleep in children with autism, but very little on the nature and causes of sleep problems in adults on the spectrum.
My PhD research studied thirty-six adults with a diagnosis of ASD and no intellectual impairment (aged 21-44 years) and a comparison group of 54 neurotypical (NT) adults (aged 22-43 years). Fifteen adults on the spectrum took medication for an associated diagnosis of anxiety/depression.
Study One: sleep difficulties and disorders
Adults with autism:
- took a significantly longer time to fall asleep
- had more brief arousals from sleep
- had poorer sleep quality compared to NT adults.
A significantly higher proportion of adults on the spectrum met criteria for insomnia in comparison to NT adults. This is consistent with findings in children with autism.
Nearly half of the adults on the spectrum had atypical timing of sleep and this was more common than for NT adults. Some adults with autism had very delayed bedtimes (later than 1:00am) while others had very early bedtimes (earlier than 9:00pm).
Study Two: evening salivary melatonin levels
Melatonin is a hormone that is secreted during the night and has been closely linked with sleep.
Adults with autism medicated for an associated diagnosis of anxiety and/or depression had lower melatonin levels in the evening before sleep compared to both NT adults and adults on the spectrum with no associated diagnoses. Lower melatonin levels were associated with poorer sleep quality in some adults with autism.
Study Three: cortisol, arousal and sleep difficulties
Cortisol is a hormone that is released in response to stress and has been closely linked with both anxiety and sleep. We showed that higher cortisol levels and reported somatic arousal symptoms (e.g., heart racing) before sleep were associated with longer night-time waking episodes and reduced sleep quality in adults on the autism spectrum.
Overall my research showed that, as with studies focused on children, poor sleep quality and insomnia are common in adults with autism. However, problems associated with irregular sleep timing are more common in adults than has been reported in children.
Based on these findings it is recommended that people who are concerned about their sleep should seek a sleep assessment so that any treatment can be appropriately tailored.
General information about a range of sleep problems can be found on the Sleep Health Foundation website.
Participants completed various sleep questionnaires, a 14-day sleep-wake diary, 14-day actigraphy assessment (objectively measures sleep) and provided seven saliva samples.