A large percentage of children with autism have a hard time falling asleep, wake up frequently in the middle of the night, and wake up early in the morning.
Now, a new study from Ben-Gurion University of the Negev’s National Autism Research Center of Israel shows that the brain waves of children with autism are weaker, or “shallower,” during sleep than those of typically developing children, particularly during the first part of the night. This indicates that the children have trouble entering the deep-sleep phase, which is the most critical aspect of achieving a restful and rejuvenating sleep experience.
The study was reported in the journal Sleep earlier this month.
Previous studies have shown that forty to eighty percent of children on the autism spectrum have some form of sleep disturbance, which creates severe challenges for the children and their families. Determining the causes of these sleep disturbances is a first critical step in finding out how to mitigate them, the researchers said in a statement.
Slow wave activity (SWA) is a measure of brain activity that is indicative of sleep quality, or so called sleep pressure. Normal sleep starts with periods of deep sleep that are characterized by high amplitude slow wave activity. A wave with a high amplitude is particularly tall, and a wave with a low amplitude is particularly short.
The researchers set out to find whether slow wave activity differs in children with autism spectrum disorder (ASD). Their findings showed that that was indeed the case: The wave pattern differs in children with ASD, the study said.
A team led by Prof. Ilan Dinstein, head of the National Autism Research Center of Israel and a member of Ben-Gurion University’s Department of Psychology, examined the brain activity of 29 children with autism and compared them to 23 children without autism. The children’s brain activity was recorded as they slept during an entire night in the Sleep Lab at Soroka University Medical Center, managed by Prof. Ariel Tarasiuk.
Recordings taken during the experiment revealed that the brain waves of children with autism are, on average, 25% weaker — or “shallower” — than those of typically developing children.
Children with ASD “exhibited significantly weaker SWA power, shallower SWA slopes, and a decreased proportion of slow wave sleep in comparison to controls,” the researchers said in their study. “This difference was largest during the first two hours following sleep onset and decreased gradually thereafter.”
The researchers “found a clear relationship between the severity of sleep disturbances as reported by the parents and the reduction in sleep depth,” said Prof. Dinstein in a statement. “Children with more serious sleep issues showed brain activity that indicated more shallow and superficial sleep.”
This could be because children with autism, and especially those whose parents reported serious sleep issues, “do not tire themselves out enough during the day, do not develop enough pressure to sleep, and do not sleep as deeply,” Dinstein said.
Now that the team has identified the potential physiology underlying these sleep difficulties, they are planning several follow-up studies to discover ways to generate deeper sleep and larger brain waves, from increasing physical activities during the day to behavioral therapies, and pharmacological alternatives such as medical cannabis, the statement said.
The research was supported by the Simmons Foundation Autism Research Initiative.