Why You Can't Yell in Dreams - Understanding REM Sleep Behavior Disorder

Understanding Dreams and Dreaming

Dreams are experiences and images that occur during sleep. They can be vivid and feel intensely real, or be vague and fleeting. Dreams occur during the rapid eye movement (REM) stage of sleep when brain activity is high and resembles that of being awake. It is during REM sleep when we have our most vivid dreams.

During REM sleep, the body undergoes atonia which is muscle paralysis. The brain paralyzes the major voluntary muscle groups during REM sleep, which prevents us from "acting out" our dreams. Some common facts about dreaming:

• Everyone dreams but not everyone remembers their dreams
• Dreams help process emotions and solidify memories
• Most dreams last only 5 to 20 minutes
• Dream content connects to aspects of real life experiences

Why We Can't Yell in Dreams

There are a few reasons why people can't yell or speak loudly in their dreams:

1. Muscle paralysis during REM sleep prevents vocalization - During REM sleep the body undergoes muscle paralysis or atonia. This prevents movements during vivid dream activity. Though the muscles associated with speech and vocalization are paralyzed, people may "speak" in their dream but are unable to manifest audible noises.
2. Lack of coordination between breathing and speech - Coordinated breathing is needed to produce loud vocal sounds. But during REM sleep, breathing becomes irregular. This breathing irregularity interferes with generating the air pressure and breathing rhythm required for loud vocalization.
3. Dulled senses and perception of sound - During dreams our senses are dulled compared to waking life. This affects our perception of sound including our internal sense of vocalization and hearing. Yelling or loud voices may occur in dreams but the sleeper does not perceive the loud volume.
4. Dreams manifest symbolically - Rather than literal experiences, dreams speak through symbols and metaphors. A feeling of frustration in a dream may manifest as trying unsuccessfully to yell instead of directly experiencing loud angry yelling.
5. Brain wave differences - Waking life and REM sleep have different brain wave patterns. The active cerebral cortex during REM dreams may not coordinate with other areas of the brain needed to produce loud prolonged vocal sounds.

When People Can Yell in Dreams

Though rare, some people may actually yell out loud during REM sleep. Circumstances when this can occur include:

• Sleep talking - Some individuals routinely talk during sleep without realizing it. Sleep talking can range from mumbles to loud vocalizations.
• Sleep walking - Yelling while sleepwalking can manifest as shouting during REM sleep.
• Night terrors - Screaming can occur during night terrors, episodes of fear and panic during deep non-REM sleep.
• REM sleep behavior disorder - This neurological condition causes people to physically act out vivid dreams and nightmares, sometimes including yelling.

Understanding REM Sleep Behavior Disorder

REM sleep behavior disorder (RBD) is a condition where individuals act out their dreams during REM sleep, sometimes yelling or screaming. Under normal REM sleep, muscles undergo paralysis and relaxation. But in RBD muscle paralysis is incomplete or absent, enabling complex motor behavior while dreaming.

RBD is considered a parasomnia, an abnormal behavior during sleep. It can put the dreamer and their bed partner at risk of injury from physical acting out of vivid dreams.

Symptoms of REM Sleep Behavior Disorder

Symptoms of RBD include:

• Yelling, screaming, shouting
• Kicking, punching, arm flailing
• Jumping out of bed
• Grabbing onto persons or objects
• Vocal sounds and speech
• Sudden limb muscle jerks
• Violent thrashing movements

These behaviors can lead to injuries to the person or their bed partner. Self-harm and falling out of bed are risks. Most episodes occur in the later part of the night during REM dream sleep.

Upon awakening, people with RBD often recall vivid dreams and nightmares. They have no memory of their behaviors during the episode. Bed partners are often the first to recognize and report symptoms of RBD sleeping behaviors.

Causes and Risk Factors for RBD

REM sleep normally includes atonia muscle paralysis. But for those with REM behavior disorder, certain neurological factors prevent normal atonia:

• Brainstem pathology - Areas of the brainstem coordinate REM atonia. Neurodegeneration in these areas can prevent normal REM paralysis.
• Neurotransmitter imbalances - Reduced levels of neurotransmitters GABA and glycine which inhibit motor neurons during REM can lead to RBD.
• Medications - Some antidepressants and other drugs that alter neurotransmitters are associated with a higher RBD risk.

Risk factors for developing REM sleep behavior disorder include:

• Being male - RBD is much more common in men than women.
• Older age - Onset is typically after age 50.
• Neurodegenerative diseases - Many with RBD later develop synucleinopathies Parkinson's and Lewy body dementia.
• Narcolepsy - Between 33-66% of those with narcolepsy also experience RBD symptoms.

Diagnosing REM Sleep Behavior Disorder

Diagnosing RBD involves both a medical history and polysomnogram sleep study. Diagnostic approaches include:

• Medical history - Description of symptoms and sleeping behaviors from the patient and bed partner.
• Sleep questionnaires - Assessments like the RBD Screening Questionnaire (RBDSQ) and the REM Sleep Behavior Disorder Questionnaire (RBDQ).
• Polysomnogram - Sleep study monitoring brain waves, muscle activity, breathing, heart rate, and limb movements during sleep.
• Electromyography (EMG) - Measures electrical activity in muscles during the sleep study.

These diagnostic tests help confirm loss of muscle atonia during REM sleep along with unusual motor activity and behaviors.

Treatment Options for REM Sleep Behavior Disorder

While RBD has no definitive cure, various treatment options can help reduce symptoms and risk of injury. Management approaches include:

• Medications - Clonazepam and melatonin are commonly used to treat RBD and restore normal REM atonia.
• Safety precautions - Padding bed rails, removing hazardous objects from the room, sleeping on the floor can help prevent injury.
• Treating underlying conditions - Managing associated neurological disorders like Parkinson's disease or narcolepsy may improve RBD.
• Cognitive Behavioral Therapy - CBT helps patients adjust thoughts and behaviors related to their disorder.

Since RBD often indicates an increased risk for neurodegenerative disease, ongoing monitoring for emerging neurological disorders is also recommended.

The Link Between RBD and Neurodegenerative Diseases

RBD is strongly associated with the later development of certain neurodegenerative diseases, in particular:

• Parkinson's disease
• Dementia with Lewy Bodies
• Multiple system atrophy

Studies indicate over 80% of individuals diagnosed with RBD will eventually develop a neurodegenerative disorder. Development of these diseases typically occurs within 5 to 15 years after diagnosis of REM behavior disorder.

The onset of RBD symptoms may precede diagnosis of these other conditions by many years. RBD is now considered a warning sign or early marker of alpha-synuclein brain pathology linked to Parkinson's and Lewy body disease.

Theories on the RBD-Neurodegenerative Link

Disclaimer: This article is for informational purposes only and does not constitute medical advice. Always consult with a healthcare professional before starting any new treatment regimen.