Diagnosis and Management of Clinical Conditions That Occur During Sleep
Core concepts
This domain covers disorders whose defining events happen in sleep: obstructive and central sleep apnea, sleep-related hypoventilation, parasomnias (NREM arousal disorders, REM sleep behavior disorder, sleepwalking, sleep terrors, nightmares), sleep-related movement disorders (periodic limb movement disorder, restless legs syndrome, bruxism, rhythmic movement disorder), and sleep-related epilepsy. The candidate must know the diagnostic architecture: the ICSD-3 categories, the Apnea-Hypopnea Index (AHI) and oxygen desaturation index thresholds, and the AASM scoring rules for hypopneas (≥30% flow reduction with ≥3% desaturation or an arousal).
Management anchors
OSA: PAP is first-line for moderate-severe disease (AHI ≥15, or ≥5 with symptoms/comorbidity); alternatives include mandibular advancement devices, positional therapy, weight management, hypoglossal nerve stimulation, and upper airway surgery in selected patients. Central sleep apnea with Cheyne-Stokes respiration in heart failure: optimize heart failure therapy first; adaptive servo-ventilation is contraindicated in symptomatic heart failure with ejection fraction ≤45%. RBD: confirm with polysomnography (REM without atonia), counsel on bedroom safety, and treat with melatonin or clonazepam. NREM parasomnias: safety counseling, treat triggers (sleep deprivation, alcohol, stress), and reserve medications for dangerous or refractory cases.
Traps
Questions often blur NREM versus REM parasomnias: NREM events arise from slow-wave sleep early in the night, are amnestic, and are common in children; RBD occurs in REM (later in the night), with dream enactment and recall, and predicts synucleinopathies. Another trap is labeling all apneas as obstructive-central apneas lack effort and cluster with heart failure, opioids, and stroke. Do not diagnose RLS by nocturnal leg movements alone; RLS is a clinical diagnosis with an urge to move that worsens at rest and in the evening.
Rule of thumb
If a patient acts out dreams violently in the second half of the night and remembers it, think RBD, not sleepwalking.