Rhythmic movement disorder is common in young children. A person with RMD moves in a repetitive manner, especially movements involving the neck and upper torso. This happens just before sleep (Stage 0) and just after (Stage 1). The episodes last under 15 minutes. Over sixty percent of nine-month-old infants experience it to some degree. By age four, only eighteen percent of children still have these movements.
RMD usually disappears naturally by age 5. Studies have estimated RMD continues in 6% of 5-year-olds and in 3% of 13-year-olds. At these later ages the condition is rare enough that it can be considered a sleep disorder, although it is still benign in the large majority of cases. Adults who have RMD may find it embarrassing and irritating to others.
Most children and adults who have rhythmic movement disorder are healthy, although the condition is more common in children with autism and other developmental disabilities. For most affected children, RMD is a self-limiting condition that does not require treatment. For those who suffer from particularly violent body rolling or body rocking movements, protective padding in the crib or bed can prevent injuries. Controlled sleep restriction has been found to have some benefit. In extreme cases, doctors sometimes use the anticonvulsant drug clonazepam (which can be addictive) or the antidepressant citalopram to slow or stop the movements.
Another name for this disorder is jactatio capitis nocturna.