Rythmic movement disorder

Rhythmic Movement Disorder, also referred to as jactatio capitis nocturna, is a condition characterized by repetitive banging or rocking motions just before and during light sleep. This condition occurs primarily in infants and young children, although adults can be affected as well. While rarely harmful, it can be alarming or confusing to parents or others who witness it occurring.

Symptoms
The symptoms of this condition are characterized by repetitive movements of certain areas of the body, usually the head and neck. There are varying types of movement which may be seen, including: RMD most commonly affects otherwise healthy children but may also be seen in association with autism and other developmental disabilities.
 * The head is forcibly moved in a back and forward direction - head-banging type
 * The head is moved laterally while in a supine (lying on the back, face up) position - head-rolling type
 * The whole body is rocked while on the hands and knees - body-rocking type
 * The whole body is moved laterally while in a supine position - body-rolling type

Causes
There is very little literature or consensus available as to the cause of this condition, although some theories have been put forth. It is sometimes considered to be affected by hyperactivity and certain autistic tendencies. Some parents may become concerned that the behavior is intended to be self-harming (eg. banging the head on the mattress repeatedly), although observations of people with this condition indicate that this is very rarely the case.

When asked by adults why they "rock" themselves to sleep it has been offered that it is a calming and soothing way to fall asleep, often reminding them of being an infant and being coddled to sleep by a parent or caregiver. It is often a learned response when babies are taught to "self soothe" and also provides the child warmth through body movement.

Treatment
Although sometimes disconcerting for parents to witness, RMD is usually a benign behavior which typically resolves itself by age five. For most affected children, RMD is a self-limited condition that does not require treatment. For youngsters exhibiting particularly violent movements, use of protective padding in the crib or bed is often helpful.