Emma Baker, Murdoch Children’s Research Institute, OTARC Alumni, on the types and causes of sleep problems in Autistic adults

Much research has been done on sleep in Autistic children, but very little on the nature and causes of sleep problems in Autistic adults.

My PhD research studied thirty-six adults with a diagnosis of Autism and no intellectual impairment (aged 21-44 years) and a comparison group of 54 non-autistic adults (aged 22-43 years). Fifteen Autistic adults took medication for an associated diagnosis of anxiety/depression.

Method

Participants completed various sleep questionnaires, a 14-day sleep-wake diary, 14-day actigraphy assessment (objectively measures sleep) and provided seven saliva samples.

The results are summarised below.

Study One: sleep difficulties and disorders

Autistic adults:

• took a significantly longer time to fall asleep
• had more brief arousals from sleep
• had poorer sleep quality compared to non-autistic adults.

A significantly higher proportion of Autistic adults met criteria for insomnia in comparison to non-autistic adults. This is consistent with findings in Autistic children.

Nearly half of the Autistic adults had atypical timing of sleep and this was more common than for non-autistic adults. Some Autistic adults 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.

Autistic adults medicated for an associated diagnosis of anxiety and/or depression had lower melatonin levels in the evening before sleep compared to both non-autistic adults and Autistic adults with no associated diagnoses. Lower melatonin levels were associated with poorer sleep quality in some Autistic adults.

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 Autistic adults.

Overall my research showed that, as with studies focused on children, poor sleep quality and insomnia are common in Autistic adults. 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.