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Overview of Abnormal Movements During Sleep

CE Publish Date: February 15, 2024
CE Expiration Date: February 15, 2027
CEU (Continuing Education Unit):2 Credit(s)
AGD Code: 730

Educational Aims

This self-instructional course for dentists aims to define disorders associated with abnormal movements during sleep; offer a comprehensive view of the impacts, symptoms, and treatment of these disorders; and provide common language that dentists can use with other medical providers.

Expected Outcomes

Dental Sleep Practice subscribers can answer the CE questions online to earn 2 hours of CE from reading the article. Correctly answering the questions will demonstrate the reader can:

  • Understand how abnormal-movement sleep disorders are categorized
  • Understand how to take an appropriate patient history
  • Realize which diagnostic studies are required
  • Recognize the value in referring patients with symptoms of these movement disorders to the appropriate specialist

Dr. Amalia A. Geller explores abnormal movements during sleep, their impacts and treatment.

Abnormal movements

by Amalia A. Geller, MD

Abnormal movements during sleep are common in early life — with between 15% to 20% of children experiencing this condition, and 4% continuing to have abnormal movements during sleep into adulthood.

Abnormal movements during sleep can be divided into two categories:

  1. Simple behaviors (single movements, repetitive, and periodic): These occur during the transition from wake to sleep or from sleep to wake and occur during stages N1 and/or N2 (NREM) sleep.
  2. Complex behaviors (sleep talking, sleepwalking, night terrors, and dreaming enactment): Complex movements are disruptive and interfere with the control mechanisms within stages N1, N2, N3, and REM sleep.

We will focus on understanding how these disorders are categorized as well as understanding how to take an appropriate history, which diagnostic studies are required, and ultimately a summary of management tactics.

It is important to note that both simple abnormal movements and complex movements can be seen during seizures, dissociative states, psychiatric episodes, or during periods of metabolic derangement (hypoglycemia).

Simple movements can be normal during childhood such as disorders of arousal, nightmares, and benign myoclonic jerks during infancy.

Simple, Abnormal Movements

  1. Hypnic Jerks

These are brief jerks of a whole body or can involve segments of the body. They primarily occur when falling asleep. They can occur at any age and are, for the most part, considered benign. They can be related to sleep deprivation, excessive caffeine intake, and can be associated with visual as well as auditory and tactile behaviors. They are sometimes known as “sensory starts” which are associated with hallucinations without motor involvement.

  1. Exploding Head Syndrome

This is a benign sensory parasomnia. It is the sensation of hearing a loud sound during sleep-wake/wake-sleep transitions. It is multi-sensory and painless. In ICD3 coding, it is termed as “other parasomnias.” Often, it is misdiagnosed as a sub-arachnoid hemorrhage but usually not associated with any other signs or symptoms. Rarely, it can be associated with muscle jerks and twitching. More than 80% of those diagnosed have a feeling of impending doom and often will have tachycardia.

  1. Propriospinal Myoclonus

This is associated with flexion or extension of the abdomen, trunk, or neck. This can occur during wakeful drowsiness (stage one sleep). It can occur throughout the day, and if so, is associated with spinal cord pathology. There is no evidence that it is only associated with sleep onset or structural nerve damage. MRIs are usually normal, but one in five people with this condition may have a focal lesion found in the spinal cord.

  1. Epileptic Myoclonus

This is associated with sudden jerks of the limbs associated with waking or soon after waking. It is often seen in children and teenagers. It is very important to rule out juvenile myoclonic epilepsy (Primary Generalized Epilepsy).

  1. Benign Myoclonus of Infancy (a.k.a. Benign Neonatal Sleep Myoclonus)

This condition includes brief bilateral, symmetric jerks of the limbs during NREM sleep in young infants. It occurs within the first few weeks of life, and it usually resolves by 2 to 3 months of age. It is often misdiagnosed as seizures. It only occurs during sleep, unlike myoclonic epilepsy that can occur during wakefulness. Infants go on to have normal development.

Bruxism is thought to be a “protective” reflex attempt to open the airway and increase masseter tone.

  1. Sleep Related Bruxism (SRB)

SRB involves rhythmic and non-rhythmic clenching, jerking, and grinding of the muscles of mastication. It primarily occurs at sleep onset, with or without arousals, multiple times throughout the night. The outcome is usually dental wear, TMJ disorder, and headache. The anxiety trigger associated with bruxism is localized to the limbic part of the basal ganglia. Bruxism is thought to be a “protective” reflex attempt to open the airway and increase masseter tone. The brain goes into “survival mode” which activates the sympathetic nervous system to the open airway. The jaw pushes forward, and grinding bottom teeth press against the top to increase the volume of the airway.

In Upper Airway Resistance, narrowing between the retro-palatal and retroglossal areas lead to being unable to enter REM sleep. A similar condition that can occur with bruxism is Oral Mandibular Dystonia (OMD). OMD is different because it is a sustained or intermittent muscle contraction and occurs later during the day, but not upon awakening like bruxism. The age of onset in OMD is in the fourth or fifth decades of life, whereas bruxism is childhood onset. Consider the patient with daily frontal headaches for bruxism. Patients with blepharospasm or cervical dystonia are at increased risk for bruxism.

The primary differentiating feature for nocturnal leg cramps versus other sleep-related leg movements is the sustained muscle contraction.

  1. Nocturnal Leg Cramps

This condition is defined by painful, sustained muscle contractions involving the calf, foot, and thighs. It can occur any time during the night during any sleep stage. The duration of action can be seconds to minutes. The primary differentiating feature versus other sleep-related leg movements is the sustained muscle contraction.

Periodic or Rhythmic Movements

  1. Sleep-Related Rhythmic Movement Disorder

This involves large groups of muscles such as rolling and body rocking. It occurs in early childhood with sleep onset and is associated with normal development. When it involves interference with function, then it becomes known as Sleep Related Rhythmic Movement Disorder. It rarely affects adolescents and adults. Examples of factors involved would be obstructive sleep apnea and restless leg syndrome.

  1. Hypnagogic Foot Tremor

This condition involves rapid, rhythmic movements occurring in only one foot at sleep onset and into light N2 sleep. It is not pathologic.

  1. Alternating Leg Muscle Activation (ALMA)

This is activation of the anterior tibialis muscle in one leg with alternating in the other leg during sleep. It is associated with arousals and not associated with any awareness. It can be associated with breathing-disordered sleep and periodic limb movements during sleep. It can be a side effect of taking serotonin reuptake inhibitors.

  1. Periodically Movement Disorders During Sleep

This condition is associated with clinically significant cortical arousals. Its repetitive movements occur every 5 to 90 seconds. It can only be diagnosed by polysomnography; it is not a clinical diagnosis. It occurs primarily during the first half of the night in stage 2 sleep. An increase of this condition is noted in the elderly with or without neurological problems.

Complex Movements and Behaviors: NREM Parasomnias

Disorders of Arousal

This is a mixture of both NREM and wake where the two states combine. This could be due to the inability to fully allow or inhibit arousal from sleep, and it is primarily characterized by minimal cognitive function, amnesia, and features of appearing awake. This can be very common in children and adolescents. Triggers involve:

  • Acute sleep deprivation
  • Stress
  • Breathing-disordered sleep

Examples of disorders of arousal include sleepwalking, confusional arousals, sleep terrors, and sleep-related eating disorders.

Sleep-related eating disorder is a mixture of being awake and in NREM. It includes recurrent, involuntary amnestic eating of peculiar foods. There could be partial or no memory of the event. It can be associated with sedative hypnotics. For example, women on 5mg or greater of zolpidem have experienced sleep talking, sleep driving, confusional arousals, and sleep eating. It can also be associated with Restless Leg Syndrome.

However, a differentiation exists between the Sleep-Related Eating Disorder and Night Eating Syndrome (NES). NES is recurrent episodes of hyperphagia during wakefulness, occurring in the middle of the night. It can lead to a delay in the circadian pattern of eating.

Complex Movements and Behaviors: REM Parasomnias

  1. Recurrent Isolated Sleep Paralysis

Partial or complete inability to move; the intrusion and persistence of REM sleep-related atonia into wake. Events can be remembered for years later. Leads to a sense of impending doom and can occur as an isolated symptom. Triggers include:

  • Sleep deprivation
  • Childhood PTSD
  • Chronic pain
  • Depression
  1. Nightmare Disorder

Complex visual imagery experienced during REM sleep carries over into wakefulness. It is usually associated with recall. It can involve motor components such as screaming, abrupt awakening, and sudden jerking. Violent dream enactment though is not nightmares. Nightmares are not night terrors (NREM/slow wave sleep). There is recall with nightmares, but usually no recall with night terrors.

  1. REM Behavior Disorder

A pathologic loss of muscle paralysis (atonia) associated with vocalizations and complex movements. It is primarily seen in older men who have the beginnings of neurodegenerative diseases such as Parkinson’s Disease, multiple system atrophy, and dementia with Lewy body disease. It can be the harbinger of Alpha synuclein neurodegeneration. Young people who exhibit REM Behavior Disorder can have comorbidities with narcolepsy or exposure to serotonin reuptake inhibitors. It has also been associated with PTSD with or without traumatic brain injury.

  1. Vocalizations

Vocalizations are common. They can be simple vocalizations or complex vocalizations and can be associated with sleep-related behaviors. They can occur with disorders of arousal. The primary difference between “physiological sleep talking” and Disorders of Arousal with REM sleep is when it involves the inclusion of motor behaviors. An example is expiratory groaning (carathrenia); this is a prolonged expiratory vocalization occurring during REM sleep. Carathrenia is often associated with obstructive sleep apnea.

  1. Nocturnal Epilepsy 

This can involve focal seizures and can be associated with stereotypical complex behaviors. The primary feature of seizures versus parasomnias is seizures are stereotyped. Sleep-related Hypermotor Epilepsy is also known as Nocturnal Frontal Lobe Epilepsy. It can occur in late childhood to adulthood. A patient’s EEG is usually normal during wakefulness.

  1. Panic/Dissociative Events

Most dissociative events are diurnal and associated with a history of post-traumatic stress disorder or major mood disorder.

Evaluation of Abnormal Movements and Behaviors During Sleep

The first goal is to obtain a clear patient history to rule out if there is any chance for self-harm and to determine the trigger(s). There are two questionnaires that can be helpful.

The Mayo Sleep Behavior Questionnaire contains 16 questions and can help distinguish between REM Behavior Disorder and Restless Leg symptoms. The FLEP Scale helps differentiate between frontal lobe epilepsy and parasomnias.


A complete history of the patient’s experience(s) should include the following categories:

  • Predisposing factors
  • Event description
      • Eyewitness
      • Time of the night
      • Are they simple movements or complex movements?
      • Are they nocturnal seizures or psychiatric?
  • Duration of the event
      • REM versus NREM
      • REM Behavior Disorder: brief, lasting only seconds, rarely more than a minute.
      • Disorders of Arousal: seconds to minutes.
      • Frontal Lobe Epilepsy: behavioral and variable. Can last 30 seconds to 60 seconds.
      • Psychiatric: can last 30 minutes up to an hour.
  • Variable versus stereotype behaviors
      • Stereotype: seizures (with the exception of Rhythmic Movement Disorder and Periodically Movement Disorder during sleep)
      • Polymorphic: less-likely seizure
  • Eyes open versus eyes closed
      • Disorders of Arousal: Eyes open
      • Complex Movement Disorder/REM Behavior Disorder: Eyes closed
  • Memory recall
      • REM Behavior Disorder: Recall
      • Disorders of Arousal: No recall
      • Seizures: may have a recall if the seizure is brief and does not involve both temporal lobes. When both temporal lobes are involved, patients will have decreased memory recall.
  • Age of onset
      • NREM Parasomnia: Early childhood onset; resolved by adolescence
      • REM Behavior Disorder: Older adult onset. In younger age groups, it could be related with narcolepsy.
  • Family history of nocturnal events

The first step in the physical examination should be to detect if there are any signs of trauma, such as tooth wear, bruises on the body, or tongue biting.


The following triggers should be evaluated for each patient:

  1. Poor sleep hygiene
  2. Sleep deprivation
  3. Circadian disturbance
  4. Fever infection
  5. Emotional stress
  6. Medication used
  7. Alcohol/sedatives/herbal supplements
    • Non-benzodiazepine receptor agonists: zolpidem, zaleplon, and eszopiclone. These drugs are known to cause complex sleep-related behaviors such as sleep eating, sleep driving, and sleepwalking.
  1. Medical problems
    • COPD
    • hypoglycemia
    • gastroesophageal reflux disease (GERD)
    • congestive heart failure
    • renal disease
    • neurological disease
  1. Family history: genetic issues are often associated with arousals from NREM sleep
  2. Other Sleep Disorders
    • Obstructive Sleep Apnea will aggravate Disorders of Arousal such as with bruxism, epilepsy, and Rhythmic Movement Disorder.
    • Narcolepsy
    • Periodic Movement Disorder during sleep often causes a sleep disruption followed by daytime fatigue and daytime sleepiness.

Physical Examination 

The first step in the examination should be to detect if there are any signs of trauma, such as tooth wear, bruises on the body, or tongue biting. Then, check for signs of sleep fragmentation disorder, such as obstructive sleep apnea (hypertension increased, increased BMI, crowded nasopharynx, and posterior nasopharynx). Finally, if REM Behavior Disorder is indicated, look for signs of Parkinson’s disease such as cognitive impairment — lack of arm swing, mask-like faces, orthostatic hypotension, and hypokinesis.

Management of Abnormal Movements and Behaviors During Sleep

Although the management of abnormal movements during sleep is usually overseen by a neurologist or sleep neurologist, the basics involve the following:

  1. Identifying the triggers.
  2. For Periodic Movement Disorders, implementing treatment options such as a foot wrap (Restiffic) and pharmacological agents with dopamine agonists and gabapentin.
  3. For Parasomnias of unclear ideology, the most important aspect is to keep the patient safe. Patients should maintain an event diary and be referred to neurology for a video EEG.

For a closer look at Restless Legs Syndrome, one of the abnormal movements during sleep, check out this CE:

Author Info

Abnormal movementsAmalia A. Geller, MD, is a board-certified Adult and Pediatric Neurologist with a subspecialty board certification in Sleep Medicine and additional post graduate fellowship training in Epilepsy and neurophysiology. She had a pediatric internship at Arnold Palmer Hospital for women and children and post graduate training in Child Neurology at the University of California at San Diego. Dr. Geller’s Neurophysiology and Epilepsy fellowships were performed at University of California at Irvine and her Sleep Medicine fellowship at the University of Texas Southwestern in Dallas. She is a full-time sleep medicine physician at Saint Alphonsus Sleep Medicine Center in Boise, Idaho. Her areas of interest include developing collaboration with sleep medicine dentists, orthodontists, oral myofunctional therapists, as well as ENT specialists for an integrative approach to pediatric sleep, focusing on airway management in malocclusion. Dr. Geller believes a comprehensive holistic integrative approach is what is imperative to treat children as a whole in order for them to achieve their maximum potential. Dr. Geller is the Nevada medical director for Nexus Dental Systems.


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