Parents and caregivers invest a great deal of time and care into helping their babies and young children develop good sleep habits. In the course of doing so, they may observe their children rocking their bodies back and forth while falling asleep or during sleep. Parents may also notice their children banging their heads against the bars of their cribs, rolling their heads or bodies from side to side, or making other repetitive, meaningless motions.
Parents and caregivers may, quite naturally, find these behaviors disturbing . However, sleep-related rhythmic movements are common and typically go away as a child grows older. But if these movements cause harm or sleep problems, or if they continue into adolescence and adulthood, they may amount to sleep-related rhythmic movement disorder.
What Is Sleep-Related Rhythmic Movement Disorder?
Sleep-related rhythmic movement disorder consists of broad, simple, and repeated movements before or during sleep. These movements are different from seizures , jerks, or tremors. They can affect the head, the limbs, or the entire body. Children with rhythmic movement disorder may also make rhythmic noises such as loud humming.
For most children, sleep-related rhythmic movements are a normal part of early development. Rhythmic movements are quite common in infancy, with 59% of 9-month-old babies showing some type of this behavior. This percentage decreases dramatically with age: at 18 months the percentage is cut almost in half to 33%, and by 5 years old only 5% of children are still affected.
Rhythmic movements by themselves are not abnormal and do not necessarily constitute a disorder. To be considered a disorder, the movements must interfere with sleep, impair functioning during the day, or cause injury or increase its risk.
Types of Rhythmic Movements
People with rhythmic movement disorder may display one or more types of repeated movement. In babies and children, the most common of these are head banging, head rolling, and body rocking.
- Head banging: The child forcefully and repeatedly strikes their head against the mattress, pillow, headboard, wall, or slats of the crib.
- Head rolling: The child rolls their head from side to side, generally while lying on their back.
- Body rocking: The child may rock their entire body forward and backward while on all fours, or they may move only the upper part of their body while sitting up.
Other, less common movements include leg banging, body rolling, and leg rolling.
These actions may occur before sleep, when the child is drowsy, as well as during any stage of sleep. They may also occur when the child is quietly listening to music or when they are a passenger in a moving car. Each individual movement may last only a second or two, and an entire episode often lasts less than 15 minutes.
The child may stop the movement if interrupted. Most of the time, if asked the next day, they do not remember engaging in these behaviors.
Of these movements, head banging can be the most alarming for a parent to observe. However, even though head banging can cause loud noises, it usually does not lead to significant injury.
Adults with rhythmic movement disorder also exhibit repetitive motions of the head and body .
Symptoms of Rhythmic Movement Disorder
The main symptoms of rhythmic movement disorder are the repeated rocking, rolling, and banging motions themselves. The disorder can also cause disturbed sleep in those who are affected and their bed partners, as well as make them tired during the day. The lack of sleep can contribute to problems with behavior, memory, and concentration .
Rhythmic movement disorder rarely leads to serious harm, but it may cause embarrassment for affected individuals. Infants and children with rhythmic movement disorder may lose patches of hair from banging their heads or experience other minor injuries.
Causes of Rhythmic Movement Disorder
The exact cause of rhythmic movement disorder is not well understood , but researchers have offered several theories about why this condition occurs in children.
One possibility is that the movements are a self-soothing practice. Babies and children may rock their bodies or move their heads to help them return to sleep after waking or if they are unable to fall asleep. These motions may be similar to those they had experienced in the womb, before being born, or to the feeling of being rocked to sleep by a parent.
Another theory suggests that these movements occur because the child’s nervous system has not developed enough to control motor functions during sleep. This idea is supported by the tendency for these movements to decrease with age. The movements themselves may even stimulate the development of motor control.
Researchers have identified and proposed several factors that may increase the risk of developing this disorder:
- Age: Babies one year old or younger are most likely to exhibit these behaviors. On average, body rocking appears at 6 months, head banging at 9 months, and head rolling at 12 months.
- Mental and emotional conditions: Anxiety and depression may occur at higher rates with rhythmic movement disorder in both children and adults. In people with learning disabilities or ADHD, rhythmic movement disorder may be less likely to go away as the person gets older.
- Family history: Rhythmic movement disorder may occur in some families more than in others. Researchers have observed the disorder in identical twins and triplets. It is unclear whether this points to a genetic link or whether rhythmic movements are behaviors that children learn.
- Developmental disabilities: Studies have linked both autism and Down syndrome to a higher instance of rhythmic movement disorder. However, people with these disabilities tend to make the movements throughout the day, not only around bedtime.
- Other sleep disorders: Rhythmic movement disorder may be associated with several other sleep disorders, such as sleep apnea, restless legs syndrome, and narcolepsy.
Most people with rhythmic movement disorder, including children and adults, have no other abnormalities either of development or intelligence.
When to Talk to a Doctor
Sleep-related rhythmic movements rarely require medical intervention. However, if the movements are interfering with sleep or could result in injury, connect with a physician for evaluation and advice.
Diagnosing Rhythmic Movement Disorder
To diagnose rhythmic movement disorder, doctors often perform a physical examination and collect a detailed medical history, including information about sleep habits. This can involve keeping a sleep diary, and making video recordings of the patient’s sleep. Doctors may also recommend a sleep study.
These diagnostic steps allow doctors to rule out other medical conditions, including epilepsy, that could cause abnormal movements. They also help doctors identify any underlying causes of the disorder.
Treatments for Rhythmic Movement Disorder
Many cases of rhythmic movement disorder in young children do not require any type of treatment, aside from reassurance that the condition is normal and most often temporary.
Managing the disorder in babies and children largely involves protecting the child’s safety . If there is a risk of injury to an infant, talk with a doctor about whether taking steps, such as adding padding around the inside of the crib, may help protect the child. Take care when considering making changes to the crib, and follow the principles for reducing the risk of sudden infant death syndrome (SIDS) . A pediatrician can give specific advice about safety improvements.
If another sleep disorder could be the cause of the rhythmic movements, treating the underlying disorder may offer relief. For example, research has shown that treating sleep apnea, for instance with a CPAP machine or weight loss, may clear up the rhythmic movement disorder in people diagnosed with both conditions.
For serious cases of rhythmic movement disorder, doctors may prescribe medication.
Outlook for People with Rhythmic Movement Disorder
Most children with rhythmic movement disorder grow out of it, often at or before the age of 5. In the rare cases where the disorder persists, or when it develops in older people, treatments and coping strategies can make the condition more manageable.