Sleep-Wake Disorders

Q: What is the defining feature of all sleep-wake disorders?

A: Daytime distress or impairment due to sleep problems.

Q: What 3 aspects of sleep are typically disrupted in sleep-wake disorders?

A: Quality, timing, and amount.

Q: What are the two main diagnostic approaches used in DSM-5 sleep disorders?

A: Lumping and splitting.

Q: What does “lumping” mean in DSM-5 sleep disorders?

A: Combining related conditions into one diagnosis (e.g., insomnia disorder).

Q: What does “splitting” mean in DSM-5 sleep disorders?

A: Dividing disorders into subtypes based on biological differences (e.g., narcolepsy).

Q: Why does DSM-5 use a simpler classification than ICSD-3?

A: To improve clinical usability and reliability.

Q: What test measures physiological activity during sleep?

A: Polysomnography.

Q: What does sleep latency measure?

A: Time it takes to fall asleep.

Q: What does sleep efficiency measure?

A: Percentage of time asleep while in bed.

Q: What is REM sleep primarily associated with?

A: Vivid, story-like dreams.

Q: What percentage of sleep is REM sleep?

A: About 20–25%.

Q: Which NREM stage is the deepest sleep?

A: N3 (slow-wave sleep).

Q: When does N3 sleep typically occur?

A: First third of the night.

Q: How often do REM cycles occur?

A: Every 80–100 minutes.

Q: What is “sleep-onset REM”?

A: REM sleep occurring within 15 minutes of sleep onset.

Q: What is the core complaint in insomnia disorder?

A: Dissatisfaction with sleep quantity or quality.

Q: What are the 3 main insomnia symptoms?

A: Difficulty initiating sleep, maintaining sleep, or early awakening.

Q: How often must insomnia occur for diagnosis?

A: At least 3 nights per week.

Q: What duration is required for insomnia disorder?

A: At least 3 months.

Q: What key condition must be present despite insomnia symptoms?

A: Adequate opportunity for sleep.

Q: What is episodic insomnia?

A: 1–3 months duration.

Q: What is the defining symptom of hypersomnolence disorder?

A: Excessive sleepiness despite ≥7 hours of sleep.

Q: Name the 3 possible key symptom of hypersomnolence disorder.

A: recurrent lapses into sleep on same day, prolonged nonrestorative sleep episodes, difficulty being fully awake after abrupt awakening.

Q: How long must symptoms last?

A: At least 3x per week for at least 3 months.

Q: What is a nonrestorative sleep episode?

A: Long sleep (>9 hours) that is not refreshing.

Q: What are the hallmark symptoms of narcolepsy?

A: Recurrent periods of an irrepressible need to sleep, lapsing into sleep, or napping.

Q: What is cataplexy?

A: Sudden loss of muscle tone triggered by emotion.

Q: What neurotransmitter deficiency is linked to narcolepsy?

A: Hypocretin (orexin).

Q: What REM-related abnormality is seen in narcolepsy?

A: REM latency ≤15 minutes.

Q: What distinguishes narcolepsy type 2 from type 1?

A: Type 2 has no cataplexy and no confirmed hypocretin deficiency.

Q: How often must narcolepsy sleep attacks occur for diagnosis?

A: At least 3 times per week for the past 3 months.

Q: In long-standing narcolepsy, what typically triggers cataplexy?

A: Laughter or joking.

Q: In children or early-onset narcolepsy, how can cataplexy appear?

A: Grimacing, jaw-opening, tongue thrusting, or generalized hypotonia.

Q: What CSF hypocretin-1 level is considered diagnostic for narcolepsy?

A: Less than or equal to 110 pg/mL, or less than or equal to one-third of normal values.

Q: What sleep study finding supports narcolepsy on overnight polysomnography?

A: REM latency less than or equal to 15 minutes.

Q: What multiple sleep latency test finding supports narcolepsy?

A: Mean sleep latency less than or equal to 8 minutes plus 2 or more sleep-onset REM periods.

Q: What is one key difference between narcolepsy and hypersomnolence disorder?

A: Narcolepsy involves REM abnormalities and may include cataplexy.

Q: A patient has sleep attacks, cataplexy, and low hypocretin. Which narcolepsy type fits best?

A: Narcolepsy type 1.

Q: A patient has sleep attacks and a positive MSLT, but no cataplexy. Which narcolepsy type fits best?

A: Narcolepsy type 2.

Q: What defines obstructive sleep apnea?

A: Airway obstruction causing apneas/hypopneas.

Q: What is the minimum number of apneas/hypopneas per hour required for OSA with symptoms?

A: At least 5 per hour.

Q: What number of apneas/hypopneas per hour alone is sufficient for diagnosis (even without symptoms)?

A: 15 or more per hour.

Q: What are common nighttime breathing symptoms in OSA?

A: Snoring, gasping, or breathing pauses.

Q: What daytime symptom is commonly associated with OSA?

A: Excessive sleepiness or fatigue.

Q: What is the defining physiological problem in central sleep apnea?

A: Reduced or absent respiratory effort during sleep.

Q: What distinguishes obstructive apnea from central apnea?

A: Obstructive = airway blockage; central = no respiratory effort.

Q: What is the minimum number of central apneas per hour required for diagnosis?

A: 5 or more per hour.

Q: What characterizes idiopathic central sleep apnea?

A: Apneas due to unstable respiratory control without airway obstruction.

Q: What is the defining breathing pattern in Cheyne-Stokes breathing?

A: Crescendo-decrescendo tidal volume with periodic apneas.

Q: What causes central sleep apnea in opioid-related cases?

A: Suppression of respiratory rhythm generators in the brainstem.

Q: How is severity of central sleep apnea determined?

A: Frequency of events, oxygen desaturation, and sleep fragmentation.

Q: How does hypoventilation differ from sleep apnea?

A: Hypoventilation = reduced breathing; apnea = pauses in breathing.

Q: What is the core physiological problem in sleep-related hypoventilation?

A: Decreased respiration leading to elevated CO₂ levels.

Q: If CO₂ is not directly measured, what can suggest hypoventilation?

A: Persistently low oxygen saturation without apneas/hypopneas.

Q: What defines idiopathic hypoventilation?

A: No identifiable cause.

Q: What is congenital central alveolar hypoventilation?

A: A rare condition present from birth with impaired automatic breathing.

Q: What type of conditions commonly cause comorbid hypoventilation?

A: Pulmonary, neuromuscular, chest wall disorders, or medications.

Q: What causes circadian rhythm sleep disorders?

A: Misalignment between internal clock and environment.

Q: What two types of sleep disruption can circadian rhythm disorders cause?

A: Insomnia and/or excessive sleepiness.

Q: What is delayed sleep phase type?

A: Sleep occurs later than desired.

Q: What is advanced sleep phase type?

A: Sleep occurs earlier than desired, with early awakening.

Q: What is irregular sleep-wake type?

A: No consistent sleep pattern across a 24-hour period.

Q: What is shift work type?

A: Sleep disruption due to nontraditional work hours.

Q: What is non-24-hour type?

A: Sleep cycle drifts later each day.

Q: What distinguishes non-24-hour type from delayed sleep phase type?

A: Non-24-hour involves a continuous daily drift, not a stable delay.

Q: What specifier is used when (Circ. Rhyt) symptoms last ≥3 months?

A: Persistent.

Q: Key feature of NREM arousal disorders?

A: Recurrent episodes of incomplete awakening (1st third of sleep episode).

Q: What is the typical level of responsiveness during an episode?

A: Reduced responsiveness to others.

Q: What facial expression is commonly seen during sleepwalking?

A: Blank or staring expression.

Q: What behavior defines sleepwalking episodes?

A: Getting out of bed and walking during sleep.

Q: After awakening, how aware is the individual of the episode?

A: Usually unaware (amnesia present).

Q: What is “sexsomnia”?

A: Sleep-related sexual behavior during sleepwalking.

Q: What is the typical first sign of a sleep terror episode?

A: A panicked scream.

Q: What type of arousal accompanies sleep terrors?

A: Intense autonomic arousal (e.g., tachycardia, sweating).

Q: Can individuals be easily comforted during sleep terrors?

A: No.

Q: What is a key difference between nightmares and sleep terrors?

A: Nightmares involve vivid recall; sleep terrors involve amnesia.

Q: What sleep stage are nightmares associated with?

A: REM sleep.

Q: What sleep stage are sleep terrors associated with?

A: NREM sleep (N3).

Q: Why do nightmares typically occur in the second half of the sleep episode?

A: Because REM sleep is more frequent later in the sleep episode.

Q: What level of alertness follows awakening from a nightmare?

A: Full alertness and orientation.

Q: What is the emotional tone of nightmares?

A: Dysphoric and threat-related.

Q: What type of content do nightmares typically involve?

A: Threats to survival, security, or physical integrity.

Q: How well are nightmares remembered upon waking?

A: They are well-remembered and vivid.

Q: How does awakening from a nightmare differ from a sleep terror?

A: Nightmares → alert and oriented; sleep terrors → confused and disoriented.

Q: What does the “during sleep onset” specifier indicate?

A: Nightmares occurring at sleep onset rather than later in the night.

Q: What duration qualifies as persistent nightmare disorder?

A: 6 months or longer.

Q: What duration qualifies as subacute nightmare disorder?

A: Greater than 1 month but less than 6 months.

Q: What is the key feature of REM sleep behavior disorder (RBD)?

A: Acting out dreams with movement/vocalization.

Q: What is the normal muscle state during REM sleep that is disrupted in RBD?

A: Atonia (muscle paralysis).

Q: What happens when REM atonia is absent?

A: The individual acts out their dreams.

Q: What types of behaviors are seen in RBD?

A: Vocalizations and complex motor behaviors (e.g., punching, kicking).

Q: Do RBD episodes commonly occur during naps?

A: No, they are uncommon during daytime naps.

Q: What is the level of awareness after an RBD episode?

A: Fully awake, alert, and oriented.

Q: What is a major safety concern in RBD?

A: Injury to self or bed partner.

Q: How does RBD differ from nightmare disorder behaviorally?

A: RBD involves acting out dreams; nightmares do not.

Q: How does RBD differ from sleepwalking in timing?

A: RBD occurs later in the night; sleepwalking occurs early.

Q: How does RBD differ from sleep terrors in recall?

A: RBD has vivid recall; sleep terrors have amnesia.

Q: What is the core symptom of restless legs syndrome (RLS)?

A: Urge to move legs with uncomfortable sensations.

Q: When do RLS symptoms worsen?

A: At rest and in the evening/night.

Q: What relieves RLS symptoms?

A: Movement.