What causes acting out dreams during sleep?

Causes of Acting Out Your Dreams

The primary causes of acting out dreams during sleep include REM sleep behavior disorder (RBD), which can be isolated/idiopathic, secondary to neurodegenerative diseases, or drug-induced, particularly by serotonergic medications. 1

Types of REM Sleep Behavior Disorder (RBD)

Isolated/Idiopathic RBD

• Occurs without a clear underlying disorder or inciting medication/substance 1
• Typically affects older adults, who are generally younger than those with neurodegenerative disorders but older than those with drug-induced RBD 1
• Often represents a prodromal phase of neurodegenerative disorders, particularly α-synucleinopathies 2

Secondary RBD

• Associated with neurodegenerative diseases, especially:
  • Parkinson's disease 1, 3
  • Dementia with Lewy bodies 2, 4
  • Multiple system atrophy 2, 3
• Also associated with narcolepsy type 1 2
• Approximately 57% of RBD patients have an associated neurological disorder 3
• In patients with Parkinson's disease, RBD developed before parkinsonism in 52% of cases 3

Drug-Induced/Exacerbated RBD

• Most commonly caused by serotonergic antidepressants, particularly selective serotonin reuptake inhibitors (SSRIs) 1
• Along with narcolepsy, this is the most common etiology for RBD in patients younger than 50 years 1
• Typically emerges within weeks or months after starting or increasing the dose of the inciting medication 1
• Patients with drug-induced RBD are typically younger than those with other forms of RBD 1

Clinical Manifestations

• Dream enactment behaviors vary widely from night to night and between patients 1
• Most movements are small twitches and brief jerks affecting the extremities, occurring every few seconds to minutes 1
• Complex and potentially dangerous behaviors can occur at any time during the night or course of the disorder 1
• Behaviors often involve defense against attack in dreams (87% of cases) 3
• Male predominance is strong (87% of patients), though less evident in multiple system atrophy 3
• Injury to self (32%) or assault of bed partners (64%) can occur, with serious injuries like subdural hematomas reported 3

Pathophysiology

• RBD is characterized by loss of normal muscle atonia during REM sleep (REM sleep without atonia or RSWA) 2
• This loss of atonia allows patients to physically act out their dreams 2
• In normal individuals, bizarre dream content is masked by REM sleep atonia 1
• In patients with Parkinson's disease, there is often an improvement in movements during RBD episodes compared to wakefulness 5

Diagnostic Considerations

• Diagnosis requires both clinical history of dream enactment and polysomnographic evidence of muscle activity during REM sleep 2
• Polysomnography shows sustained muscle activity (tonic activity) during REM sleep 6
• Dream content is often altered and involves defense of the sleeper against attack 3

Management Implications

• Environmental safety measures are crucial to prevent injuries 1
• Pharmacological options include:
  • Clonazepam (most commonly prescribed, effective in 87% of cases) 3
  • Melatonin (immediate-release, starting at 3 mg) 1
  • For drug-induced RBD, discontinuation of the inciting medication if safe to do so 1
• For patients requiring continued antidepressant therapy, agents with lower serotonergic profiles (like bupropion) may be better tolerated 1

Special Considerations

• RBD is common, affecting approximately 80 million patients worldwide 1
• Age is the greatest risk factor, with approximately 1 in 20 older individuals potentially having RBD 1
• Idiopathic RBD in older adults is now recognized as a strong predictor of future neurodegenerative disease development 2, 4
• Neuroimaging is unlikely to reveal underlying disorders not suspected clinically 3

Understanding the cause of dream enactment is essential for proper management and for identifying patients who may be at risk for developing neurodegenerative disorders.