What Are Parasomnias and Sleep-Related Movement Disorders?

Sleep is often thought of as a time when the body and mind completely switch off. In reality, the brain remains highly active, coordinating complex processes that support memory, healing, metabolism and emotional well-being. When these processes are disrupted, however, sleep can become anything but restful.

Some people may walk through their house while asleep, unknowingly grind their teeth throughout the night, or experience repeated leg movements that leave them exhausted the next morning. These conditions fall into two distinct categories: parasomnias and sleep-related movement disorders. Although they may appear similar, they differ in their causes, symptoms and treatment approaches.

Parasomnias are undesirable behaviours or experiences that occur during sleep or while transitioning between sleep and wakefulness. They occur when the brain partially awakens from sleep, causing a person to perform actions without full awareness.

These episodes are often more common in children but can occur at any age. While some are harmless and disappear over time, others may interfere with sleep quality or signal an underlying neurological condition.

Common parasomnias include sleepwalking, sleep talking, night terrors, confusional arousals, nightmares and REM Sleep Behaviour Disorder (RBD), a condition in which people physically act out their dreams because the normal muscle paralysis during REM sleep is absent. RBD is particularly important because it may precede certain neurodegenerative disorders, including Parkinson's disease, by several years.

Unlike parasomnias, sleep-related movement disorders involve simple, repetitive and often involuntary movements that interrupt sleep rather than complex behaviours.

One of the most recognised examples is Restless Legs Syndrome (RLS), characterised by an uncomfortable urge to move the legs, particularly during periods of rest or before bedtime. Another common condition is Periodic Limb Movement Disorder (PLMD), in which repetitive leg jerks occur throughout the night, often without the individual being aware of them.

Other disorders in this group include sleep bruxism, rhythmic movement disorder and sleep-related leg cramps. Although these movements may seem minor, repeated sleep interruptions can significantly reduce sleep quality, leading to fatigue, impaired concentration, mood disturbances and reduced daytime productivity.

There is rarely a single cause. Instead, these conditions usually result from a combination of neurological, genetic, environmental and lifestyle factors.

Sleep deprivation, chronic stress, anxiety, irregular sleep schedules, alcohol consumption and certain medications can increase the likelihood of parasomnias. Meanwhile, sleep-related movement disorders are frequently associated with iron deficiency, kidney disease, pregnancy, peripheral neuropathy and neurological disorders such as Parkinson's disease.

Researchers also believe that changes in the brain circuits responsible for regulating movement and sleep contribute significantly to many of these disorders.

Occasional sleep talking or a single episode of sleepwalking is usually not a cause for alarm. However, recurring episodes that affect sleep quality or pose a risk of injury deserve medical attention.

Warning signs include:

• Frequent sleepwalking or violent movements during sleep

• Acting out dreams or falling out of bed

• Persistent leg discomfort before bedtime

• Repetitive limb movements noticed by a bed partner

• Excessive daytime sleepiness despite getting adequate sleep

• Morning headaches, jaw pain, or worn teeth from nighttime grinding

Ignoring these symptoms can lead to chronic sleep deprivation, impaired cognitive function, workplace accidents and a reduced quality of life.

Diagnosis begins with a thorough review of a person's sleep history, medical history, medications and lifestyle. Since many patients are unaware of what happens while they sleep, observations from a family member or bed partner often provide valuable clues.

If required, a sleep specialist may recommend an overnight polysomnography (sleep study), which records brain activity, breathing, heart rate, muscle activity and body movements throughout the night. Blood tests may also be performed to identify contributing factors such as iron deficiency or other underlying medical conditions.

Accurate diagnosis is essential because many sleep disorders share similar symptoms but require different treatment strategies.

The good news is that most parasomnias and sleep-related movement disorders can be managed effectively once the underlying cause is identified.

Treatment often begins with improving sleep hygiene, maintaining a regular sleep schedule, reducing stress, limiting alcohol intake and addressing medical conditions that may be contributing to symptoms. In some cases, medications or behavioural therapies may be recommended. At the same time, safety measures - such as removing sharp objects or securing the sleep environment are important for individuals who sleepwalk or experience violent dream enactment.

Emerging research is also exploring the role of cannabinoid-based medications in improving sleep in certain patients, particularly where chronic pain, anxiety, or neurological disorders coexist with sleep disturbances. While evidence continues to evolve, these therapies are being investigated for their potential to support sleep quality in carefully selected patients under medical supervision.

Sleep disorders are more than an inconvenience; they can affect nearly every aspect of physical and mental health. Persistent disruptions may increase the risk of cardiovascular disease, depression, anxiety, metabolic disorders, impaired memory and reduced daytime performance.

Recognising unusual nighttime behaviours early and seeking professional evaluation can lead to timely treatment, better sleep quality and a healthier, more productive life.