New Pediatric Sleep Order Clarifies Restless Sleepers

Children with restless legs at bedtime may now confirm their predicament is different from restless legs syndrome (RLS) or periodic limb movement disorder (PLMD).1,2

Restless sleep disorder (RSD) describes a condition identified in approximately 7 percent of children ages 6 to 18 who make large movements all night long during sleep.

How is it different from RLS and PLMD? And might adults also have RSD?

Movement disorders of sleep

Up until this year, children who actively moved in their sleep were offered 2 sleep disorder diagnoses: RLS and PLMD.

Restless legs syndrome (RLS)

This sleep disorder affects all ages. It describes unpleasant sensations in the legs—often described erroneously as “growing pains” in children — which prevent falling asleep.

RLS can happen at any time of day, but it’s most problematic at bedtime. People with RLS may go to considerable lengths to calm their jumpy, twitchy legs so they can sleep. They may also finally fall asleep and then awaken in the middle of the night and experience more of these sleep-stealing sensations. The sleep lost as a result, night after night, can lead to sleep deprivation and all of its associated daytime symptoms.

Common causes of RLS can include iron deficiency, pregnancy, genetics, use of antidepressants, and caffeine or alcohol use.1 However, in children, the chief causes become limited mostly to low blood iron and inheritance of the condition from their parents.

Period leg movement disorder (PLMD)

Both children and adults may also experience this sleep disorder. It describes repetitive movement patterns in the feet and legs (and sometimes the arms) occurring only while asleep. The movements follow a rhythm in clusters that last between 20 and 40 seconds each.

The chief problem with PLMD? It fragments sleep architecture, shortchanging the sleeper a night of adequate quality sleep. The root cause of PLMD remains mysterious. Researchers think that, like RLS, it relates to low iron levels. It could also be linked to the use of certain medications.

Two conditions, diabetes and kidney disease, may lead to neurological problems which result in these rhythmic patterns of movement. Narcolepsy and sleep-related eating disorders have associations with PLMD. Also to blame? Genetic conditions.

What makes RSD different from RLS and PLMD?

RSD describes problems in children with movement during sleep which far exceed behaviors in other movement disorders of sleep.

Typically, a case of RLS happens prior to sleep, whereas PLMD’s movements are small in size. However, descriptions such as “thrashing” or “wrestling” or “sleeping like a helicopter” are common in cases of RSD.3,4

Dr. Lourdes DelRosso, a sleep physician at the University of Washington and Seattle Children’s Hospital, first launched formal inquiries into the possibility of RSD. In August, she presented its now formalized diagnostic criteria, which required 18 months to complete and involved a 10-person international task.

Why is an RSD diagnosis important?

DelRosso pursued this line of research after facing the desperate needs of multiple families with children who would literally fall out of bed from restless movement. RSD leads to difficulties with classroom focus as well as emotional and behavioral challenges caused by nightly fragmented sleep.

Criteria for an RSD diagnosis include:5

  • Complaints of restless sleep
  • Witnessed large body movements
  • Confirmation of at least 5 large body movements during a sleep study
  • Frequency of at least 3 times weekly over at least 3 months
  • Clinically significant impairment
  • Ruling out other causes for restless sleep (such as RLS or PLMD)

Formalizing this new disorder means many families may find more and better relief a lot sooner for their restless sleepers.

Benefits for the sleep medicine field

DelRosso, too, thinks this newly unveiled condition will be useful to her peers in sleep medicine.

"For many years, those of us in sleep medicine have recognized a pattern of sleep that affected a child’s behavior but didn’t fit the criteria for other known sleep disorders or conditions...” DelRosso said. “This work provides consensus on a definition and diagnostic criteria for RSD, offering a new tool to help more children suffering from restless sleep.5

DelRosso further suspects that the sympathetic nervous system may have a key role in RSD and devotes her attention now to this potential link.6

Once RSD is diagnosed, iron supplementation quickly treats it. DelRosso is currently studying the use of both oral and intravenous iron to treat RSD. One of her patients has participated in one such approach with good success.

For those on waiting lists for pediatric sleep studies, the sleep physician recommends a diet rich in iron, with foods like spinach, certain kinds of cereals, and meat to bolster iron supply in the blood.3

Can adults also experience RSD?

DelRosso’s research is confined to the pediatric population. She cannot say whether adults might also experience RSD, but she hopes this new distinction will inspire other sleep researchers toward research targeting the adult population.7

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