Observing head shaking during sleep, either in yourself or a loved one, can be concerning. Sleep-related movements are common, but their repetitive or forceful nature often prompts a search for answers. While many instances of head shaking are benign, understanding the underlying cause is the first step. The movement’s nature, such as its rhythmicity or severity, helps distinguish between harmless sleep phenomena and potential medical or neurological conditions.
Identifying Rhythmic Movement Disorder (RMD)
The most frequent cause of head shaking during sleep, particularly in infants and young children, is Rhythmic Movement Disorder (RMD). This disorder is classified as a parasomnia, involving abnormal behaviors or movements that occur during sleep. The specific form of RMD involving the head is often referred to by its older name, Jactatio Capitis Nocturna (JCN), which translates to “nighttime head banging.”
RMD is characterized by stereotyped, repetitive movements of large muscle groups, typically the head, neck, or trunk. The movements often include rocking, rolling the head side-to-side, or banging the head forward into the pillow or headboard. These rhythmic actions usually occur as a person is falling asleep or during the lighter stages of non-rapid eye movement (NREM) sleep.
These movements can be intense enough to disturb a bed partner or parent, with the frequency often ranging from 0.5 to 2 cycles per second. For infants and toddlers, RMD is frequently a transient physiological phenomenon, often beginning in the first year of life and resolving spontaneously before the child reaches five years old. It is considered benign unless the movements lead to injury or significantly fragment sleep, resulting in daytime impairment.
Other Common Sleep-Related Movements
Not all movements involving the head or neck during sleep are RMD; other common sleep phenomena can be mistaken for head shaking. Hypnic jerks, also known as sleep starts, are sudden, brief, involuntary muscle contractions that occur as a person is drifting off to sleep. These jerks can sometimes involve the head or neck, but they are isolated events, unlike the sustained, repetitive motions seen in RMD.
Other benign parasomnias can also involve head or body movement. Sleep talking and confusional arousals are non-REM sleep disorders that may cause a person to sit up or move, sometimes including a sudden head motion. Unlike RMD, these movements are usually non-rhythmic and are often accompanied by vocalizations or signs of partial awakening.
While Restless Legs Syndrome (RLS) is primarily known for the urge to move the legs, it can be associated with Periodic Limb Movement Disorder (PLMD), where repetitive muscle contractions occur. Though typically in the lower limbs, these movements may rarely manifest in the upper body or trunk, causing movements distinct from the side-to-side head shaking of RMD. These movements are generally brief and not as consistently rhythmic as RMD.
When Head Shaking May Indicate a Medical Condition
While most sleep movements are benign, persistent or severe head shaking may point toward a less common neurological condition. One such condition is Sleep-Related Hypermotor Epilepsy (SHE), previously known as Nocturnal Frontal Lobe Epilepsy (NFLE). SHE seizures typically occur during sleep and can cause complex motor behaviors, including violent movements of the head, arms, and legs.
These epileptic events differ from RMD because they are usually very brief, lasting less than two minutes. They often involve dramatic, non-rhythmic movements like cycling, twisting, or posturing. They tend to occur frequently, sometimes multiple times in a single night, and are often confused with severe parasomnias or night terrors. A key differentiating factor is the presence of abnormal electrical activity in the brain, detectable by an electroencephalogram (EEG).
Another potential cause is Essential Tremor (ET) that manifests during sleep, although ET often lessens or stops completely when the person is asleep. ET is a neurological disorder characterized by a rhythmic, involuntary shaking that often affects the hands, but can also involve the head, presenting as a “yes-yes” or “no-no” motion. If head shaking is part of a tremor that persists into the lighter sleep stages, a neurological evaluation may be necessary.
Consulting a Specialist
Seeking a professional evaluation is appropriate if the head shaking movements are causing concern. Clear “red flags” that warrant a consultation with a sleep specialist or neurologist include movements that result in self-inflicted injury or pose a significant safety risk. An evaluation is also recommended if the movements continue frequently into adulthood or increase in intensity or frequency over time.
A specialist may recommend a nocturnal video-polysomnography (PSG), a comprehensive sleep study. This test simultaneously records brain activity (EEG), muscle activity, breathing, and video footage of the movements. This allows doctors to accurately distinguish between parasomnias, seizures, and other movement disorders. For benign RMD, simple management techniques focus on safety, such as padding the bed’s headboard or moving the bed away from walls.
Treatment for RMD is not always necessary, especially for children whose movements are expected to resolve naturally. If RMD is severe, or if a more serious condition like SHE is diagnosed, treatment may involve medication. The most important step is often addressing any coexisting sleep disorders, such as obstructive sleep apnea or restless legs syndrome, which can sometimes trigger the rhythmic movements.