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ABIM Sleep Medicine study materials
ABIM Sleep Medicine study resources

ABIM Sleep Medicine practice questions

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Question 1Normal Sleep and Sleep-Wake Regulation

In a healthy young adult, which sleep stage occupies the largest proportion of total sleep time?

  1. Stage R sleep
  2. Stage N1 sleep
  3. Stage N3 sleep
  4. Stage N2 sleep Correct answer.

Explanation

Stage N2 typically accounts for roughly 45-55% of total sleep time in adults, making it the most abundant stage. Slow-wave sleep and REM each occupy roughly 20-25%, and N1 is only about 5%.

Question 2Normal Sleep and Sleep-Wake Regulation

Which EEG feature is the defining marker of stage N2 sleep?

  1. Sawtooth waves with rapid eye movements
  2. Posterior dominant alpha rhythm
  3. Slow eye movements with low-amplitude mixed frequency EEG
  4. Sleep spindles and K-complexes Correct answer.

Explanation

Stage N2 is scored when sleep spindles or K-complexes appear in the absence of criteria for N3 or REM. These transient waveforms arise from thalamocortical and cortical generators.

Question 3Normal Sleep and Sleep-Wake Regulation

A 24-year-old records sleep for two weeks. On nights after going to bed at 3 a.m., sleep onset is short and total sleep is normal. On nights after going to bed at 10 p.m., he lies awake for over an hour. Which process best explains this pattern?

  1. Reduced total sleep need relative to age-matched peers
  2. A defect in the arousal system causing hypervigilance
  3. A circadian alerting signal opposing sleep at the early biological evening Correct answer.
  4. An intrinsic shortening of the homeostatic sleep drive

Explanation

The circadian system generates a wake-promoting signal that is strong in the early biological evening, opposing sleep pressure even when homeostatic drive is high. Advancing bedtime into this window produces prolonged sleep latency despite adequate prior wakefulness.

Question 4Normal Sleep and Sleep-Wake Regulation

The homeostatic sleep drive in the two-process model is best indexed by which measure?

  1. Core body temperature nadir
  2. Amount of slow-wave activity in subsequent sleep Correct answer.
  3. Plasma melatonin onset
  4. Theta activity during waking EEG

Explanation

Process S is the homeostatic component, and slow-wave activity in non-REM sleep is its most widely used electrophysiologic marker, rising with prior wake duration. The other measures reflect circadian timing or waking state rather than accumulated sleep pressure.

Question 5Normal Sleep and Sleep-Wake Regulation

Which description best characterizes the normal temporal pattern of REM sleep across a night of sleep in a healthy adult?

  1. REM sleep occurs only after the first 3 hours of sleep
  2. REM periods are longest in the first sleep cycle
  3. REM periods lengthen progressively across successive cycles Correct answer.
  4. REM sleep is evenly distributed across all cycles

Explanation

REM periods are short early in the night and lengthen in later cycles, so most REM sleep occurs in the final third of the night. This distribution explains why late-night awakenings disproportionately truncate REM.

Question 6Normal Sleep and Sleep-Wake Regulation

Which brain region serves as the principal circadian pacemaker in mammals?

  1. Locus coeruleus of the pons
  2. Ventrolateral preoptic nucleus
  3. Pedunculopontine tegmental nucleus
  4. Suprachiasmatic nucleus of the hypothalamus Correct answer.

Explanation

The suprachiasmatic nucleus generates endogenous circadian rhythms and synchronizes them to light via the retinohypothalamic tract. The other structures govern arousal or sleep promotion rather than timekeeping.

Question 7Normal Sleep and Sleep-Wake Regulation

Which photoreceptor class is most important for entraining circadian rhythms to light?

  1. Rods
  2. Cones
  3. Bipolar cells
  4. Melanopsin-containing intrinsically photosensitive retinal ganglion cells Correct answer.

Explanation

Intrinsically photosensitive retinal ganglion cells expressing melanopsin project to the suprachiasmatic nucleus and mediate non-image-forming circadian responses. Rods and cones contribute but are not the principal circadian photoreceptors.

Question 8Normal Sleep and Sleep-Wake Regulation

A night-shift worker asks how to shift her sleep schedule to adapt to working 11 p.m. to 7 a.m. Which strategy is most consistent with circadian principles?

  1. Bright light in the early portion of the night shift and avoidance of morning light before daytime sleep Correct answer.
  2. Bright light at midday and an unchanged nighttime sleep schedule
  3. Bright light exposure in the early morning after the shift and a fixed daytime bedtime
  4. Dim light throughout the night shift with morning light exposure

Explanation

To delay the circadian clock for night work, light should be timed to the early biological night (start of the shift) and morning light, which would advance the clock, should be avoided before daytime sleep. This combination produces the desired phase delay.

Question 9Normal Sleep and Sleep-Wake Regulation

Melatonin secretion from the pineal gland is primarily regulated by which mechanism?

  1. Direct sympathetic input driven by the suprachiasmatic nucleus via the paraventricular nucleus Correct answer.
  2. Feedback from circulating cortisol
  3. Parasympathetic vagal tone from the brainstem
  4. Stretch receptors in the third ventricle

Explanation

The SCN signals the paraventricular nucleus, which relays via the intermediolateral cell column to the superior cervical ganglion and then to the pineal gland. This sympathetic pathway drives nocturnal melatonin synthesis.

Question 10Normal Sleep and Sleep-Wake Regulation

Which statement about the normal ontogeny of sleep is accurate?

  1. Slow-wave sleep proportion is highest in infancy and rises through adolescence
  2. Total sleep time remains constant from infancy through adulthood
  3. REM sleep proportion is highest in premature infants and declines with age Correct answer.
  4. Circadian rhythmicity is fully established at birth

Explanation

Premature and newborn infants spend a large fraction of sleep in REM (active) sleep, and this proportion falls progressively with maturation. Slow-wave sleep peaks in childhood and declines thereafter, circadian rhythms mature postnatally, and total sleep time decreases across development.

Question 11Normal Sleep and Sleep-Wake Regulation

During a normal transition from wakefulness to stage N1 sleep, which change is expected?

  1. Disappearance of alpha rhythm and emergence of slow eye movements Correct answer.
  2. Onset of rapid eye movements and muscle atonia
  3. Emergence of high-amplitude delta waves
  4. Appearance of alpha rhythm over occipital regions

Explanation

Sleep onset is marked by attenuation of the posterior alpha rhythm and replacement with low-amplitude mixed-frequency EEG, often with slow rolling eye movements. Rapid eye movements with atonia and delta waves occur in later stages.

Question 12Normal Sleep and Sleep-Wake Regulation

Which best describes the normal pattern of muscle tone across sleep stages?

  1. Tone is lowest in stage N3 and highest in REM
  2. Tone is uniformly absent in all sleep stages
  3. Tone is lowest in REM and reduced but present in non-REM sleep Correct answer.
  4. Tone is highest in REM and lowest in stage N1

Explanation

Skeletal muscle atonia is a hallmark of REM sleep, produced by active inhibition of motor neurons, whereas non-REM sleep shows reduced but preserved tone. This distinction underlies the use of chin EMG in staging.

Question 13Normal Sleep and Sleep-Wake Regulation

A researcher wants to estimate circadian phase from salivary samples collected at home under dim light. Which marker is most appropriate?

  1. Peak cortisol amplitude
  2. Dim-light melatonin onset Correct answer.
  3. Core temperature maximum
  4. Nocturnal growth hormone surge

Explanation

Dim-light melatonin onset is the standard salivary and plasma marker of circadian phase because melatonin secretion is tightly coupled to the internal clock and suppressed by light. The other measures are less reliable phase markers or are influenced by sleep itself.

Question 14Normal Sleep and Sleep-Wake Regulation

Which neurotransmitter system is most central to generating wakefulness through the ascending arousal system?

  1. Serotonergic neurons of the raphe during REM atonia
  2. GABAergic neurons of the ventrolateral preoptic nucleus
  3. Cholinergic neurons of the basal forebrain during N3
  4. Orexin/hypocretin neurons of the lateral hypothalamus Correct answer.

Explanation

Orexin/hypocretin neurons stabilize and promote wakefulness and project broadly to arousal nuclei. Loss of these neurons causes narcolepsy with cataplexy. The other options describe sleep-promoting or stage-specific systems.

Question 15Normal Sleep and Sleep-Wake Regulation

A healthy adult sleeps 6 hours nightly for a week, then sleeps 10 hours for two nights. Which pattern of recovery is most consistent with homeostatic regulation?

  1. Sleep spindles disappear during recovery sleep
  2. Slow-wave activity is elevated during recovery sleep relative to baseline Correct answer.
  3. REM latency is markedly prolonged during recovery sleep
  4. Total sleep time on recovery nights is unchanged from baseline

Explanation

Sleep deprivation increases homeostatic pressure, and recovery sleep shows increased slow-wave activity and reduced sleep latency. This rebound of slow-wave sleep reflects repayment of the homeostatic debt.

Question 16Normal Sleep and Sleep-Wake Regulation

Which EEG frequency band corresponds to the alpha rhythm seen in relaxed wakefulness with eyes closed?

  1. 8-13 Hz Correct answer.
  2. 4-7 Hz
  3. 14-30 Hz
  4. 0.5-4 Hz

Explanation

Alpha rhythm is conventionally defined as 8-13 Hz and is maximal over posterior regions during relaxed wakefulness with eyes closed. The other bands correspond to delta, theta, and beta activity.

Question 17Normal Sleep and Sleep-Wake Regulation

Which statement about the normal first sleep cycle in a healthy adult is correct?

  1. It contains the longest REM period of the night
  2. It typically contains the greatest amount of slow-wave sleep Correct answer.
  3. It is usually shorter than 20 minutes
  4. It lacks stage N2 sleep

Explanation

Slow-wave sleep is front-loaded, so the first cycle contains the largest share of N3. REM periods are shortest early and lengthen later in the night.

Question 18Normal Sleep and Sleep-Wake Regulation

A patient's sleep log shows a stable 7-hour sleep opportunity each night but a bedtime that drifts 2 hours later every weekend, with Monday insomnia. Which circadian phenomenon best explains the Monday difficulty?

  1. REM rebound from weekday deprivation
  2. Social jet lag from weekend phase delay Correct answer.
  3. Advanced sleep-wake phase disorder
  4. Homeostatic saturation from excess sleep

Explanation

Later weekend bedtimes and wake times delay the circadian clock relative to the weekday schedule, producing a mismatch termed social jet lag. The result is difficulty initiating sleep and waking at the required weekday time.

Question 19Normal Sleep and Sleep-Wake Regulation

Which best explains why newborns lack a consolidated nocturnal melatonin rhythm?

  1. Newborns lack light exposure entirely
  2. Melatonin is produced only by the retina in infancy
  3. The suprachiasmatic nucleus and its output pathways are still maturing Correct answer.
  4. The pineal gland is absent until 6 months of age

Explanation

Circadian rhythmicity emerges postnatally as the SCN and its output pathways mature and as the infant is exposed to light-dark cycles. The pineal gland is present at birth, and melatonin is not produced by the retina.

Question 20Normal Sleep and Sleep-Wake Regulation

Which change in sleep architecture is expected in a healthy older adult compared with a young adult?

  1. Longer total sleep time
  2. Increased proportion of slow-wave sleep
  3. Decreased sleep efficiency with more nocturnal awakenings Correct answer.
  4. Shorter sleep latency

Explanation

Aging is associated with reduced sleep efficiency, more awakenings, and declines in slow-wave sleep, while total sleep time and sleep latency tend to worsen rather than improve. These changes are partly circadian and partly structural.

Question 21Insomnia

According to standard diagnostic criteria, insomnia disorder requires that sleep difficulty and associated daytime symptoms be present for at least what minimum duration?

  1. Three months Correct answer.
  2. One month
  3. Six months
  4. One week

Explanation

Chronic insomnia disorder requires sleep disturbance and daytime consequences occurring at least three nights per week for at least three months. Shorter durations are classified as short-term or acute insomnia.

Question 22Insomnia

Which instrument is a validated 7-item self-report measure specifically designed to assess the severity and nature of insomnia?

  1. Pittsburgh Sleep Quality Index
  2. STOP-BANG questionnaire
  3. Insomnia Severity Index Correct answer.
  4. Epworth Sleepiness Scale

Explanation

The Insomnia Severity Index is a 7-item measure quantifying perceived insomnia severity and daytime impact, with established cutoffs for clinical significance. The other instruments screen for sleepiness, general sleep quality, or sleep apnea risk.

Question 23Insomnia

Which sleep hygiene recommendation is most appropriate to give a patient with chronic insomnia?

  1. Consume a caffeinated beverage in the evening to relax
  2. Use the bed for reading and watching television to build sleepiness
  3. Keep a consistent wake time and limit time in bed to actual sleep Correct answer.
  4. Take long daytime naps to compensate for lost nighttime sleep

Explanation

Stimulus control principles emphasize a fixed wake time and restricting time in bed to approximate actual sleep, strengthening the bed-sleep association. Daytime napping, evening caffeine, and non-sleep bed activities all undermine these goals.

Question 24Insomnia

Stimulus control therapy for insomnia is best described by which instruction set?

  1. Go to bed only when sleepy, leave the bed if awake and return only when sleepy, and rise at a fixed time Correct answer.
  2. Avoid all physical activity in the four hours before bedtime
  3. Delay bedtime progressively later each week until sleep onset normalizes
  4. Spend at least ten hours in bed each night to maximize opportunity for sleep

Explanation

Stimulus control re-establishes the bed as a cue for sleep by limiting it to sleepy states and by enforcing a consistent arising time. It does not rely on extended time in bed or exercise restriction.

Question 25Insomnia

Which agent is a dual orexin receptor antagonist approved for the treatment of insomnia?

  1. Trazodone
  2. Suvorexant Correct answer.
  3. Zolpidem
  4. Melatonin

Explanation

Suvorexant blocks orexin receptors to promote sleep and is FDA-approved for insomnia. Zolpidem is a GABA-A modulator, trazodone an antidepressant used off-label, and melatonin a hormone supplement.

Question 26Insomnia

Cognitive behavioral therapy for insomnia (CBT-I) is recommended as first-line treatment primarily because it does what?

  1. Requires no patient effort or between-session practice
  2. Targets perpetuating cognitive and behavioral factors with durable benefit and fewer adverse effects Correct answer.
  3. Eliminates the need to evaluate for comorbid sleep disorders
  4. Produces immediate sedation comparable to hypnotics

Explanation

CBT-I addresses maladaptive thoughts and behaviors that maintain insomnia, yielding sustained improvement without medication risks. It is not sedating, requires active patient participation, and does not replace evaluation for comorbidities.

Question 27Insomnia

A patient reports difficulty initiating sleep. Which term best describes this specific insomnia symptom?

  1. Initial insomnia Correct answer.
  2. Sleep state misperception
  3. Sleep maintenance insomnia
  4. Terminal insomnia

Explanation

Initial insomnia refers to difficulty falling asleep at the start of the night. Maintenance insomnia involves awakenings during the night, and terminal insomnia involves early morning awakening.

Question 28Insomnia

A 45-year-old with chronic insomnia has a normal physical exam and no red flags. Which finding would most strongly prompt evaluation for a comorbid sleep disorder before starting hypnotic therapy?

  1. Two nighttime awakenings per week
  2. A preference for a cool bedroom
  3. Sleep-onset latency of 30 minutes
  4. Loud snoring with witnessed apneas and daytime sleepiness Correct answer.

Explanation

Snoring with witnessed apneas and sleepiness suggests obstructive sleep apnea, which must be identified because sedative-hypnotics can worsen respiratory events. The other features are common in insomnia and are not red flags.

Question 29Insomnia

Which statement about sleep restriction therapy is accurate?

  1. It requires the patient to nap daily to offset sleep debt
  2. It is contraindicated in all patients with depression
  3. It initially limits time in bed to approximate the patient's average total sleep time Correct answer.
  4. It prescribes an extended time in bed to ensure adequate sleep

Explanation

Sleep restriction therapy sets time in bed near the measured average total sleep time, then extends it gradually as sleep efficiency improves. It does not extend time in bed initially and does not rely on napping.

Question 30Insomnia

A patient's sleep diary over two weeks shows an average total sleep time of 5.5 hours with 8.5 hours in bed. What is the sleep efficiency?

  1. 65% Correct answer.
  2. 85%
  3. 55%
  4. 75%

Explanation

Sleep efficiency equals total sleep time divided by time in bed, so 5.5 divided by 8.5 is approximately 0.65, or 65%. This low efficiency supports sleep restriction therapy.

Question 31Insomnia

Which cognitive distortion is most characteristic of patients with insomnia who catastrophize about the consequences of a poor night's sleep?

  1. Accepting occasional nighttime awakenings
  2. Using relaxation before bed
  3. Believing that one bad night will ruin the next day entirely Correct answer.
  4. Keeping a consistent sleep schedule

Explanation

Catastrophic thinking amplifies the perceived threat of poor sleep and drives arousal that perpetuates insomnia. Cognitive therapy targets these exaggerated beliefs. The other options are adaptive behaviors.

Question 32Insomnia

Which medication class carries a boxed warning for complex sleep behaviors such as sleepwalking and sleep-driving?

  1. Sedating antihistamines
  2. Melatonin receptor agonists
  3. Dual orexin receptor antagonists
  4. Nonbenzodiazepine GABA-A receptor modulators (Z-drugs) Correct answer.

Explanation

Z-drugs such as zolpidem, zaleplon, and eszopiclone carry a boxed warning for complex sleep behaviors including sleepwalking and sleep-driving. Orexin antagonists, melatonin agonists, and antihistamines do not carry this class warning.

Question 33Insomnia

A patient taking a benzodiazepine for insomnia wishes to stop it. Which approach is most appropriate?

  1. Switching immediately to a higher dose of another benzodiazepine
  2. Abrupt discontinuation to avoid dependence
  3. Continuing indefinitely without reassessment
  4. Gradual tapering, often combined with CBT-I, to reduce rebound insomnia Correct answer.

Explanation

Benzodiazepines should be tapered gradually to avoid rebound insomnia and withdrawal, and CBT-I improves success in discontinuation. Abrupt cessation and indefinite continuation are both inappropriate.

Question 34Insomnia

Which feature most supports a diagnosis of psychophysiological (conditioned) insomnia rather than a circadian rhythm disorder?

  1. Sleep improves markedly when sleeping away from home Correct answer.
  2. Sleep timing shifts progressively later each night
  3. Sleep is normal on workdays but delayed on weekends
  4. Total sleep time is normal when allowed to sleep freely at a late hour

Explanation

Conditioned insomnia is tied to the home sleep environment, so sleep often improves in a novel setting. Circadian disorders show a consistent phase misalignment regardless of location, with sleep normalizing when timing matches the biological clock.

Question 35Insomnia

A 60-year-old reports difficulty staying asleep with frequent awakenings and early morning awakening, and also feels sad most days with anhedonia. Which consideration is most appropriate?

  1. Evaluate and treat the depressive disorder, which may improve the insomnia Correct answer.
  2. Prescribe a hypnotic without screening for suicide risk
  3. Treat insomnia only and defer evaluation of mood
  4. Assume the insomnia is primary and unrelated to mood

Explanation

Depression commonly presents with maintenance insomnia and early morning awakening, so comorbid mood disorders should be identified and treated. Addressing depression often improves sleep, and suicide risk should be assessed.

Question 36Insomnia

Which statement about paradoxical insomnia (sleep state misperception) is accurate?

  1. It responds best to increasing time in bed
  2. It is diagnosed only when total sleep time exceeds ten hours
  3. Patients underestimate their actual sleep time compared with objective measures Correct answer.
  4. Polysomnography shows severe sleep loss matching the patient's complaint

Explanation

In paradoxical insomnia, patients report severe insomnia but objective testing shows more sleep than perceived. Treatment includes cognitive restructuring and reassurance based on objective findings.

Question 37Insomnia

Which relaxation-based approach teaches patients to systematically tense and then release muscle groups to reduce presleep arousal?

  1. Progressive muscle relaxation Correct answer.
  2. Sleep restriction
  3. Paradoxical intention
  4. Biofeedback of sleep stages

Explanation

Progressive muscle relaxation involves sequential tensing and releasing of muscle groups to lower physiologic arousal before sleep. Paradoxical intention and sleep restriction are distinct behavioral techniques.

Question 38Insomnia

A patient with insomnia and a history of alcohol use disorder asks about using alcohol to fall asleep. What is the best response?

  1. Alcohol may hasten sleep onset but fragments sleep later and worsens insomnia over time Correct answer.
  2. Alcohol reliably increases slow-wave sleep and is recommended
  3. Alcohol has no effect on sleep architecture
  4. A single drink at bedtime is a safe long-term strategy

Explanation

Alcohol can shorten sleep latency but suppresses REM and increases later awakenings and rebound arousal, worsening insomnia chronically. It is especially problematic with a history of alcohol use disorder.

Question 39Insomnia

Which outcome best indicates that sleep restriction therapy is being applied correctly over time?

  1. Sleep efficiency rising above roughly 85-90%, prompting gradual extension of time in bed Correct answer.
  2. Reducing total sleep time indefinitely
  3. Adding daily naps to manage daytime sleepiness
  4. Increasing time in bed weekly regardless of sleep efficiency

Explanation

Time in bed is extended in increments only when sleep efficiency reaches about 85-90%, balancing consolidation with adequate sleep duration. Extension should be tied to efficiency, not arbitrary, and restriction is not indefinite.

Question 40Insomnia

A patient with chronic insomnia and untreated severe obstructive sleep apnea is being considered for sleep restriction therapy. What is the most appropriate course?

  1. Proceed with aggressive sleep restriction as first-line therapy
  2. Treat the sleep apnea first and adapt insomnia therapy, avoiding interventions that worsen sleepiness Correct answer.
  3. Start a benzodiazepine to consolidate sleep
  4. Discontinue all evaluation of sleep apnea

Explanation

In untreated severe OSA, sleep restriction can worsen daytime sleepiness and is generally avoided until apnea is treated. Therapy should be adapted and sedative-hypnotics used cautiously because they can worsen respiratory events.

Question 41Insomnia

A patient reports a sleep-onset latency of three hours, and polysomnography confirms a prolonged latency with normal sleep architecture once asleep. Which formulation best fits a circadian rather than a primary insomnia explanation?

  1. Delayed sleep-wake phase disorder Correct answer.
  2. Psychophysiological insomnia
  3. Sleep state misperception
  4. Insufficient sleep syndrome

Explanation

Delayed sleep-wake phase disorder produces a prolonged sleep-onset latency when the patient attempts an early bedtime but normal sleep when timing matches the delayed biological clock. Primary insomnia lacks this phase-dependent pattern.

Question 42Insomnia

Which pairing of medication and mechanism is correct for an agent used in insomnia?

  1. Eszopiclone: orexin receptor antagonist
  2. Suvorexant: GABA-A receptor positive modulator
  3. Ramelteon: melatonin MT1/MT2 receptor agonist Correct answer.
  4. Doxepin: histamine H1 receptor agonist

Explanation

Ramelteon is a melatonin receptor agonist acting at MT1 and MT2. Suvorexant is an orexin antagonist, eszopiclone a GABA-A modulator, and low-dose doxepin is a histamine H1 antagonist.

Question 43Insomnia

A patient completing CBT-I reports persistent sleep-onset insomnia despite good adherence. Review of the sleep diary shows a bedtime of 9 PM and a habitual morning rise of 5 AM, with sleepiness only after 11 PM. What is the most appropriate next step?

  1. Add a long-acting benzodiazepine
  2. Delay bedtime to match the observed sleepiness window while keeping the wake time fixed Correct answer.
  3. Extend time in bed earlier in the evening
  4. Discontinue CBT-I as ineffective

Explanation

The diary suggests the assigned bedtime precedes the patient's sleepiness window, so aligning bedtime with observed sleepiness while holding the wake time can improve sleep onset. Adding sedatives or extending time in bed would not address the timing mismatch.

Question 44Insomnia

Which statement about the relationship between hyperarousal and insomnia is best supported?

  1. Hyperarousal is relevant only in acute insomnia
  2. Insomnia involves increased physiologic and cognitive arousal that persists into sleep Correct answer.
  3. Insomnia is primarily a deficiency of total sleep drive with no arousal component
  4. Arousal plays no role once sleep onset occurs

Explanation

The hyperarousal model posits heightened physiologic and cognitive activation in insomnia that persists across the sleep period, evidenced by increased cortisol, heart rate, and EEG fast activity. It is not limited to acute insomnia.

Question 45Sleep-Related Breathing Disorders

A 52-year-old man with a BMI of 34 kg/m² and witnessed apneas undergoes a diagnostic polysomnogram. Which apnea-hypopnea index threshold establishes obstructive sleep apnea in an adult when the record shows predominantly obstructive events?

  1. 15 events per hour
  2. 10 events per hour
  3. 5 events per hour Correct answer.
  4. 30 events per hour

Explanation

In adults, OSA is diagnosed when the AHI is at least 5 per hour with associated symptoms or comorbidities, or at least 15 per hour regardless of symptoms. The 5/hour threshold with clinical features is the standard diagnostic criterion.

Question 46Sleep-Related Breathing Disorders

Which finding on polysomnography defines a hypopnea according to the recommended AASM scoring rule?

  1. A 30% or greater drop in airflow with 3% desaturation or an arousal Correct answer.
  2. Complete cessation of airflow for at least 10 seconds
  3. Any visible reduction in airflow lasting 10 seconds
  4. A 50% drop in airflow with no desaturation or arousal

Explanation

The recommended hypopnea rule requires a 30% or greater reduction in airflow lasting at least 10 seconds with either a 3% oxygen desaturation or an arousal. A complete cessation of airflow defines an apnea, not a hypopnea.

Question 47Sleep-Related Breathing Disorders

A 60-year-old woman with heart failure and atrial fibrillation has central sleep apnea with Cheyne-Stokes respiration. Which feature best distinguishes central from obstructive events on the polysomnogram?

  1. Events occurring only in REM sleep
  2. Presence of snoring before the event
  3. Absence of respiratory effort during the event Correct answer.
  4. Oxygen desaturation below 90%

Explanation

Central apnea is characterized by absent respiratory effort during the airflow cessation, reflecting loss of ventilatory drive. Obstructive events show continued or increased effort against an occluded airway.

Question 48Sleep-Related Breathing Disorders

Which patient population is at highest risk for obstructive sleep apnea based on anatomic and demographic factors?

  1. A 25-year-old lean man with no comorbidities
  2. A 30-year-old woman with a BMI of 22 kg/m²
  3. A postmenopausal woman with a BMI of 38 kg/m² Correct answer.
  4. A 40-year-old man with a BMI of 24 kg/m²

Explanation

Obesity and postmenopausal status in women both substantially increase OSA risk, and a BMI of 38 kg/m² is a strong risk factor. Male sex and increasing age also raise risk, but the combination of marked obesity and postmenopause carries the highest likelihood among these choices.

Question 49Sleep-Related Breathing Disorders

A 45-year-old man is diagnosed with severe OSA and is started on positive airway pressure therapy. Which measure best confirms that the therapy is effectively controlling his sleep-disordered breathing?

  1. Number of hours the device is used per night
  2. Subjective report of improved daytime energy
  3. Residual apnea-hypopnea index on the device download Correct answer.
  4. Mask leak reported by the device

Explanation

The residual AHI from device data directly quantifies remaining respiratory events on therapy and is the key objective measure of efficacy. Adherence and leak are important but do not by themselves confirm control of events.

Question 50Sleep-Related Breathing Disorders

Which clinical feature is most characteristic of the upper airway resistance syndrome compared with frank obstructive sleep apnea?

  1. An apnea-hypopnea index greater than 30 per hour
  2. A normal apnea-hypopnea index with recurrent respiratory effort-related arousals Correct answer.
  3. Absence of any arousals during sleep
  4. Persistent oxygen desaturation below 85%

Explanation

Upper airway resistance syndrome is characterized by respiratory effort-related arousals with an AHI below the diagnostic threshold for OSA. It reflects increased airway resistance without frank apneas or hypopneas.