Sleep Disorders | Sleep Review
The underlying cause of insomnia in many children with autism could be related to the neurological condition of restless legs syndrome.
By Lisa Spear
Sleep disorders, which are common in children with autism 1, are often written off as behavior problems, but emerging science is unraveling a more complex picture of the root cause of insomnia in this patient population.
New research published in the Journal of Clinical Sleep Medicine shows a significant association between sleep disorders in pediatric autism patients and Restless Legs Syndrome (RLS) .2 Often times, a child is diagnosed with insomnia, even if there are telltale signs for There is a delay in obtaining a full diagnosis, which in turn can postpone appropriate treatment.
“It’s a reminder to all of us not to necessarily take things at face value and ask the right questions,” says Dr. med. Judith Owens, MPH, professor of neurology and director of the Center for Pediatric Sleep Disorders at Harvard Medical School in Boston, who was not involved in the study.
“It is very common for parents to walk in and one of their main complaints is that the child is lying all over the bed, constantly moving, falling out of bed and throwing and turning around.” Owens encourages vendors to dig deeper when they encounter these cases. “Anything that looks like ‘insomnia’ in this population may very well have an underlying organic etiology. It’s a very important message, ”she says.
The retrospective research, conducted by scientists at Emory University in Georgia in collaboration with Nox Medical, found that restless legs may be the cause of bedtime resistance and motor restlessness in pediatric autism patients.
Scientists examined data from patient charts spanning a period of three years to examine the prevalence of RLS symptoms in children with autism spectrum disorder (ASD) and chronic insomnia.
Of a sample of 103 children treated at a sleep clinic in Atlanta, Georgia, 39% met criteria for a diagnosis of RLS. This is far greater than the roughly 2% of children in the general population who are diagnosed with RLS. 3 People with a history of obstructive sleep apnea were excluded from the study.
“We have found that a very large number of these children with insomnia meet the criteria for pediatric RLS. Without the knowledge of their parents and without the knowledge of their doctors, RLS is likely to be the cause,” says Dr. med. Jeffrey Durmer, co-author, a neurologist and sleep specialist who works as the chief medical officer for Iceland-based medical device company Nox Medical.
Night polysomnography (PSG) data, available in approximately half of the study participants, showed that those with RLS had significantly higher rates of periodic limb movements during the night compared to controls. Both kicks and body swings were seen more frequently in patients with RLS. The majority, 77%, had periodic limb movements during sleep compared to none in the control group.
Because the diagnosis of RLS in children depends on the patient explaining the symptoms they are experiencing in their own words, many pediatric patients with autism may not be diagnosed because of language or cognitive delays.
Rather than not making the diagnosis, clinicians should have a high suspicion of RLS when evaluating these patients. He encourages health care providers to seek biological evidence instead of self-reported descriptions, examine periodic limb movements during sleep tests in the laboratory, assess ferritin levels, family history, and reports of parental bedtime resistance.
If a child is rocking back and forth, kicking their legs, bumping their feet against the side of a cot, or rubbing their ankles at night, it could all be indicative of an underlying nocturnal movement disorder.
“If these behaviors appear at night, they are likely to be misunderstood as being related to autism. This can be responsible for many missed diagnostic options, ”the authors write. “Assessing children with ASD requires a more thorough study of bedtime behavior, specifically looking for the presence of motor behaviors that cluster in an evening circadian pattern, as this is a classic signal for RLS.”
Mark J. Bookkeeper, MD, a sleep specialist in California at the Stanford Center for Sleep Science and Medicine who is not part of the study, hopes this research will raise awareness of this little-known association.
“Although the connection between ADHD and RLS has been well described and known for many years, sleep and RLS doctors have little to no knowledge of the association between RLS and ASD,” says Buchführer.
Why may children with autism have a higher prevalence of RLS? Diet is a likely factor.
Many of these children are picky eaters and have extremely restricted diets that put them at risk of iron deficiency. The pathophysiology of RLS is associated with iron deficiency and dopaminergic dysfunction. 4
“It makes perfect sense that this is a population that is more prone to these particular movement disorders,” says Owens, a Boston-based pediatric sleep specialist.
In the Emory study, 89% of RLS patients had low serum ferritin levels, which indicates that their body’s iron stores were low. Many of these patients then responded positively to oral iron treatment. Those who did not get better after iron therapy were prescribed the drug gabapentin, which is regularly prescribed off-label to control RLS symptoms in children.
“Lo and behold, the therapies targeted for RLS like iron therapy and gabapentin, or a combination of both, have been remarkably effective in treating this group of children,” says Durmer.
The study acknowledged that the study had limitations due to a lack of PSG data or ferritin levels for a decent number of patients in the sample. These lack of data also highlight the many barriers to evaluating patients with autism for RLS, the authors say.
“Many caregivers immediately declined tests because they didn’t think their child would tolerate the procedure, and some studies were stopped because the child was overly excited,” the study said. “Limited tolerance to procedures is a common problem and a real barrier in assessing RLS in children with ASD.”
These barriers to diagnosis mean that extra work is even more important to understand sleep problems in patients with autism spectrum disorder. It’s easy to assume that a child with autism will have trouble falling asleep due to a behavioral problem or an inappropriately early bedtime, Owens says, but doctors should go the extra mile to check for nighttime movement disorders.
While melatonin can be helpful in certain circumstances, it encourages physicians treating the pediatric autism population to think beyond the “knee-jerk” approach of using melatonin before first dialing in the reasons for a child’s sleep disorders.
She says, “For a child with autism who cannot verbalize their symptoms, you may need to ask, What kind of movements is this child making when trying to fall asleep? That is a very important question. “
Lisa Spear is co-editor of Sleep Review.
1. Malow BA, Katz T., Reynolds AM, et al. Sleep disorders and medication in children with autism spectrum disorders: a registration study. Pediatrics. 2016; 137 (Supplement 2): S98-104.
2. Kanney ML, Durmer JS, Leu R., Trotti LM. Rethinking Bedtime Resistance In Children With Autism: Is Restless Legs Syndrome To Blame? J Clin Sleep Med. 2020; 16 (12): 2029-35.
3. Picchietti D, Allen RP, Walters AS, Davidson JE, Myers A, Ferini-Strambi L. Restless Legs Syndrome: Prevalence and Impact in Children and Adolescents – The Peds-REST Study. Pediatrics. 2007 Aug; 120 (2): 253- 66. doi: 10.1542 / peds.2006-2767.
4. DelRosso L, Bruni O. Treatment of Pediatric Restless Legs Syndrome. Adv Pharmacol. 2019; 84: 237-53.