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ABA Sleep Medicine study materials
ABA Sleep Medicine study resources

ABA Sleep Medicine practice questions

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Question 1Sleep Medicine

Which sleep stage is defined by the presence of sleep spindles and K-complexes on EEG without slow-wave activity meeting criteria for N3?

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

Explanation

Stage N2 is scored when sleep spindles or K-complexes occur in the absence of sufficient slow-wave activity, and it typically occupies the largest share of adult sleep. N1 lacks spindles and K-complexes, while N3 requires slow waves in at least 20% of the epoch.

Question 2Sleep Medicine

According to standard adult scoring criteria, stage N3 sleep is scored when slow waves occupy at least what percentage of an epoch?

  1. 10%
  2. 80%
  3. 50%
  4. 20% Correct answer.

Explanation

The AASM rule scores N3 when slow waves of 0.5-2 Hz and greater than 75 microvolts peak-to-peak occupy 20% or more of the epoch. The 20% threshold distinguishes N3 from N2 with incidental slow waves.

Question 3Sleep Medicine

A polysomnogram shows low-amplitude mixed-frequency EEG, rapid eye movements, and the lowest chin EMG tone of the night. Which stage is present?

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

Explanation

Stage R combines rapid eye movements, low-amplitude mixed-frequency EEG, and atonia reflected in the lowest chin EMG of the study. This triad distinguishes REM from the non-REM stages.

Question 4Sleep Medicine

Which hormone, released from the pineal gland, is suppressed by light exposure and helps regulate circadian timing?

  1. Thyrotropin
  2. Cortisol
  3. Melatonin Correct answer.
  4. Leptin

Explanation

Melatonin is secreted by the pineal gland primarily during darkness and provides a timing signal to the circadian system. Light exposure, especially in the blue spectrum, suppresses its release.

Question 5Sleep Medicine

Which instrument is the reference standard for objectively measuring sleep architecture in a sleep laboratory?

  1. Actigraphy
  2. Polysomnography Correct answer.
  3. Epworth Sleepiness Scale
  4. Multiple sleep latency test

Explanation

Polysomnography simultaneously records EEG, EOG, EMG, and cardiorespiratory signals, allowing direct staging of sleep and detection of respiratory events. It is the reference standard against which other measures are compared.

Question 6Sleep Medicine

Which finding on a diagnostic polysomnogram defines a hypopnea under AASM recommended criteria?

  1. A 30% or greater drop in airflow with a 3% desaturation or an arousal Correct answer.
  2. A 10-second apnea with continued respiratory effort
  3. An oxygen saturation below 90% alone
  4. Any visible reduction in airflow lasting 5 seconds

Explanation

The recommended hypopnea rule requires a 30% or greater reduction in airflow lasting at least 10 seconds, accompanied by a 3% or greater desaturation or an arousal. The alternative rule uses a 4% desaturation threshold.

Question 7Sleep Medicine

Which of the following is a cardinal symptom of narcolepsy type 1?

  1. Restless legs at bedtime
  2. Cataplexy Correct answer.
  3. Nocturnal enuresis
  4. Sleepwalking

Explanation

Cataplexy, the sudden loss of muscle tone triggered by emotion, is the hallmark of narcolepsy type 1 and reflects hypocretin deficiency. Its presence distinguishes type 1 from type 2 narcolepsy.

Question 8Sleep Medicine

Which sleep-related breathing pattern is most typical of heart failure with central sleep apnea?

  1. Sustained hypoventilation without cyclic variation
  2. Cheyne-Stokes respiration Correct answer.
  3. Isolated hypopneas during wakefulness
  4. Prolonged obstructive events in REM only

Explanation

Cheyne-Stokes respiration is a cyclic pattern of crescendo-decrescendo breathing with central apneas, driven by prolonged circulation time and unstable ventilatory control in heart failure. It is the classic central apnea pattern in that population.

Question 9Sleep Medicine

A patient reports difficulty initiating sleep at a desired bedtime and delayed sleep on weekends, with an otherwise normal sleep duration when unconstrained. Which circadian rhythm disorder best fits?

  1. Delayed sleep-wake phase disorder Correct answer.
  2. Advanced sleep-wake phase disorder
  3. Shift work disorder
  4. Irregular sleep-wake rhythm disorder

Explanation

Delayed sleep-wake phase disorder features sleep onset and offset markedly later than desired, with preserved sleep duration when the schedule is free. The pattern is stabilized by weekend catch-up sleep.

Question 10Sleep Medicine

Which medication class is first-line pharmacotherapy for rapid eye movement sleep behavior disorder when behaviors endanger the patient or bed partner?

  1. Dopamine agonists
  2. Melatonin or clonazepam Correct answer.
  3. Benzodiazepine receptor agonists such as zolpidem
  4. Selective serotonin reuptake inhibitors

Explanation

Melatonin and clonazepam are the mainstays of pharmacologic treatment for REM sleep behavior disorder, with melatonin often favored for its favorable safety profile. Environmental safety measures accompany drug therapy.

Question 11Sleep Medicine

A 55-year-old with obesity, loud snoring, and witnessed apneas undergoes polysomnography. Which index is used to quantify apnea-hypopnea severity?

  1. Apnea-hypopnea index Correct answer.
  2. Periodic limb movement index
  3. Oxygen desaturation nadir
  4. Respiratory disturbance index minus arousals

Explanation

The apnea-hypopnea index expresses the number of apneas plus hypopneas per hour of sleep and categorizes severity. The desaturation nadir and limb movement index describe different phenomena.

Question 12Sleep Medicine

Positive airway pressure therapy is titrated during attended polysomnography primarily to achieve which goal?

  1. Normalize the periodic limb movement index
  2. Eliminate all snoring regardless of oxygenation
  3. Abolish respiratory events and maintain adequate oxygenation across sleep stages and positions Correct answer.
  4. Reduce the arousal index to zero

Explanation

CPAP titration seeks the pressure that eliminates apneas and hypopneas and maintains oxyhemoglobin saturation in supine and REM sleep. Snoring and arousals usually resolve as a consequence but are not the primary titration target.

Question 13Sleep Medicine

Which feature on polysomnography most strongly supports a diagnosis of REM sleep behavior disorder?

  1. Excessive slow-wave sleep in the first cycle
  2. Loss of REM atonia with dream-enacting behaviors Correct answer.
  3. Frequent arousals from N3 sleep
  4. Sleep-onset REM periods

Explanation

RBD is defined by REM sleep without atonia, often accompanied by dream-enacting behaviors captured on video-polysomnography. The loss of normal muscle paralysis during REM is the core electrophysiologic finding.

Question 14Sleep Medicine

Which finding on a multiple sleep latency test supports narcolepsy in a patient with excessive daytime sleepiness?

  1. Absence of sleep in all naps
  2. Mean sleep latency over 15 minutes with one sleep-onset REM period
  3. Mean sleep latency of 8 minutes or less with two or more sleep-onset REM periods Correct answer.
  4. Mean sleep latency over 8 minutes with no sleep-onset REM periods

Explanation

The MSLT criterion for narcolepsy is a mean sleep latency of 8 minutes or less plus at least two sleep-onset REM periods across the naps. Adequate prior sleep and other causes of REM disinhibition must be excluded.

Question 15Sleep Medicine

A patient with insomnia is started on cognitive behavioral therapy for insomnia. Which component is central to this treatment?

  1. Stimulus control and sleep restriction Correct answer.
  2. Scheduling bedtime by random selection each night
  3. Extending time in bed to promote more sleep
  4. Routine daytime napping to reduce sleep debt

Explanation

CBT-I combines stimulus control, sleep restriction, cognitive restructuring, and relaxation training. Sleep restriction and stimulus control are the behavioral core that strengthens the bed-sleep association and consolidates sleep.

Question 16Sleep Medicine

Which condition is characterized by an irresistible urge to move the legs that worsens in the evening and is relieved by movement?

  1. Periodic limb movement disorder
  2. Nocturnal leg cramps
  3. Restless legs syndrome Correct answer.
  4. REM sleep behavior disorder

Explanation

Restless legs syndrome is a sensorimotor disorder with an urge to move the legs, worsening at rest and in the evening, relieved by movement. Periodic limb movements are the polysomnographic correlate but are a separate diagnosis.

Question 17Sleep Medicine

Which sleep stage typically predominates in the first third of the night in a healthy young adult?

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

Explanation

Slow-wave sleep (N3) is front-loaded, concentrating in the first sleep cycles, while REM sleep predominates toward morning. This distribution reflects the homeostatic drive for slow-wave sleep early in the night.

Question 18Sleep Medicine

A patient on chronic opioid therapy reports new-onset central apneas on polysomnography. Which mechanism best explains this finding?

  1. Excessive REM atonia
  2. Reduced circulation time
  3. Increased upper airway collapsibility alone
  4. Blunted chemoreceptor responsiveness to carbon dioxide Correct answer.

Explanation

Opioids depress ventilatory drive, reducing the response to hypercapnia and producing central apneas and ataxic breathing. This is a pharmacologically induced central sleep apnea pattern.

Question 19Sleep Medicine

Which measure best distinguishes obstructive from central apneas on polysomnography?

  1. Presence of respiratory effort during the airflow pause Correct answer.
  2. Sleep stage at event onset
  3. Duration of the event
  4. Degree of oxygen desaturation

Explanation

Obstructive apneas show continued or increased respiratory effort against a closed airway, whereas central apneas show absent effort. Effort channels such as belts or esophageal pressure make this distinction.

Question 20Sleep Medicine

Which agent is most appropriate for treating insomnia characterized by prolonged sleep-onset latency in a patient who must avoid dependence risk?

  1. Barbiturate
  2. Melatonin receptor agonist Correct answer.
  3. Long-acting benzodiazepine
  4. Tricyclic antidepressant at hypnotic dose

Explanation

Melatonin receptor agonists such as ramelteon promote sleep onset with minimal dependence liability. Benzodiazepines and barbiturates carry dependence and tolerance risks.

Question 21Sleep Medicine

A patient sleeps 9 hours nightly but wakes unrefreshed with morning headache and dry mouth. Which screening tool most directly assesses this presentation?

  1. Epworth Sleepiness Scale
  2. Insomnia Severity Index
  3. STOP-BANG questionnaire Correct answer.
  4. Morningness-Eveningness Questionnaire

Explanation

Morning headache, dry mouth, and unrefreshing sleep suggest obstructive sleep apnea, for which STOP-BANG is a validated screening instrument. The Epworth scale measures sleepiness but does not screen for apnea risk factors.

Question 22Sleep Medicine

Which statement about the physiology of REM sleep is accurate?

  1. Heart rate and blood pressure are lower than in N3
  2. Ventilatory response to hypercapnia is enhanced
  3. Muscle tone is elevated to protect the airway
  4. Thermoregulation is suspended and poikilothermia occurs Correct answer.

Explanation

During REM sleep, thermoregulatory control is largely suspended, so body temperature drifts toward ambient temperature. This poikilothermia accompanies skeletal muscle atonia and autonomic instability.

Question 23Sleep Medicine

A patient with treated obstructive sleep apnea on CPAP remains sleepy. Which factor most directly explains residual sleepiness from a treatment-adherence standpoint?

  1. Supine sleep position alone
  2. Insufficient nightly hours of PAP use Correct answer.
  3. Use of humidification
  4. Choice of mask type

Explanation

Residual sleepiness despite therapy is often explained by inadequate nightly PAP use, since benefit depends on cumulative hours of effective pressure. Positional and interface factors matter only insofar as they affect delivered therapy.

Question 24Sleep Medicine

Which polysomnographic pattern is most consistent with a non-REM parasomnia such as sleepwalking?

  1. Abrupt arousal from N3 with autonomic activation and subsequent amnesia Correct answer.
  2. Sleep-onset REM periods with hypnagogic hallucinations
  3. Alpha intrusion during N2 sleep
  4. Dream enactment during REM with preserved atonia

Explanation

Disorders of arousal arise from incomplete awakening out of slow-wave sleep, often with autonomic surge and little recall. They typically occur in the first third of the night when N3 is most prevalent.

Question 25Sleep Medicine

A shift worker rotating from days to nights asks how best to adapt. Which strategy is most consistent with circadian principles?

  1. Bright light exposure immediately before daytime sleep
  2. Bright light exposure during the early part of the night shift and darkness on the commute home Correct answer.
  3. Avoiding caffeine entirely during night shifts
  4. Fixed daytime sleep regardless of shift timing

Explanation

Appropriately timed bright light during the night shift and avoidance of morning light on the commute help phase-delay the circadian clock to align with night work. This reduces circadian misalignment.

Question 26Sleep-Wake Disorders and Circadian Rhythm Disorders

A 45-year-old woman reports difficulty falling asleep at night and an irresistible urge to sleep in the early evening. She wakes at 3 AM feeling refreshed and cannot return to sleep. Which circadian rhythm disorder best fits this presentation?

  1. Non-24-hour sleep-wake rhythm disorder
  2. Irregular sleep-wake rhythm disorder
  3. Advanced sleep-wake phase disorder Correct answer.
  4. Delayed sleep-wake phase disorder

Explanation

Advanced sleep-wake phase disorder is characterized by an earlier-than-desired sleep onset and early morning awakening, with sleep itself being of normal quality and duration. The early evening sleepiness and 3 AM awakening with inability to resume sleep are the defining phase-advance features. Delayed phase disorder shows the opposite pattern, and irregular or non-24-hour rhythms lack the consistent early timing seen here.

Question 27Sleep-Wake Disorders and Circadian Rhythm Disorders

Which hormone is suppressed by light exposure and is used as the primary marker of circadian phase in humans?

  1. Thyroid-stimulating hormone
  2. Melatonin Correct answer.
  3. Cortisol
  4. Leptin

Explanation

Melatonin secretion from the pineal gland is suppressed by light and rises in darkness, making its onset a reliable marker of circadian phase. Dim-light melatonin onset is the standard phase marker in circadian research and clinical assessment. The other hormones listed are not used as primary circadian phase markers.

Question 28Sleep-Wake Disorders and Circadian Rhythm Disorders

A patient with delayed sleep-wake phase disorder wants to shift sleep earlier. Which intervention schedule is most consistent with standard chronotherapy?

  1. Continuous dim light throughout the day
  2. Morning bright light exposure plus evening melatonin Correct answer.
  3. Afternoon bright light exposure plus midday melatonin
  4. Evening bright light exposure plus morning melatonin

Explanation

To advance circadian phase, light must be delivered in the morning (when it produces phase advances) and melatonin taken in the evening (which also advances phase). This combination shifts sleep timing earlier. Evening light and morning melatonin would instead delay phase.

Question 29Sleep-Wake Disorders and Circadian Rhythm Disorders

A blind patient without light perception reports a sleep pattern that drifts progressively later each day over weeks. Which disorder is most likely?

  1. Shift work disorder
  2. Jet lag disorder
  3. Advanced sleep-wake phase disorder
  4. Non-24-hour sleep-wake rhythm disorder Correct answer.

Explanation

Non-24-hour sleep-wake rhythm disorder occurs when the circadian pacemaker fails to entrain to the 24-hour day, causing sleep timing to drift progressively later (or occasionally earlier) each day. Blind individuals without light perception are the classic population because light is the dominant entraining signal. The progressive daily drift distinguishes it from fixed phase disorders.

Question 30Sleep-Wake Disorders and Circadian Rhythm Disorders

Which of the following is the most characteristic polysomnographic finding in narcolepsy type 1?

  1. Frequent arousals with increased N1 sleep
  2. Prolonged REM latency with reduced REM sleep
  3. Sleep-onset REM periods with short mean sleep latency Correct answer.
  4. Increased slow-wave sleep with reduced sleep efficiency

Explanation

Narcolepsy type 1 is characterized by rapid REM sleep onset, reflected in sleep-onset REM periods and a short mean sleep latency on the multiple sleep latency test. These findings reflect the loss of hypocretin signaling that normally stabilizes wakefulness and gates REM sleep. Reduced REM or increased slow-wave sleep are not defining features.

Question 31Sleep-Wake Disorders and Circadian Rhythm Disorders

A night-shift worker has insomnia and excessive sleepiness that began when she started rotating shifts six months ago. Which diagnosis best fits if symptoms are temporally linked to the work schedule?

  1. Delayed sleep-wake phase disorder
  2. Shift work disorder Correct answer.
  3. Narcolepsy type 2
  4. Chronic insomnia disorder

Explanation

Shift work disorder is diagnosed when insomnia and/or excessive sleepiness are temporally associated with a work schedule that overlaps the habitual sleep period. The clear link to rotating shift work and the absence of symptoms before the schedule change support this diagnosis. Chronic insomnia disorder would not require the schedule relationship, and the phase and narcolepsy diagnoses lack supporting features.

Question 32Sleep-Wake Disorders and Circadian Rhythm Disorders

Which brain region contains the master circadian pacemaker that coordinates peripheral clocks?

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

Explanation

The suprachiasmatic nucleus of the anterior hypothalamus is the master circadian pacemaker, receiving light input from the retina and synchronizing peripheral clocks. The other structures listed serve roles in arousal, melatonin secretion, or sleep promotion but do not function as the master clock.

Question 33Sleep-Wake Disorders and Circadian Rhythm Disorders

A traveler flies eastward across eight time zones and develops insomnia and daytime fatigue for several days. Which statement about jet lag disorder is most accurate?

  1. Jet lag disorder requires a polysomnogram for diagnosis
  2. Jet lag disorder resolves only with hypnotic medication
  3. Westward travel is generally harder to adjust to than eastward travel
  4. Eastward travel is generally harder to adjust to than westward travel Correct answer.

Explanation

Eastward travel requires phase advances, which are harder for the circadian system to achieve than the phase delays needed after westward travel, so eastward jet lag is typically more severe and longer lasting. Jet lag disorder is a clinical diagnosis and usually resolves spontaneously as re-entrainment occurs.

Question 34Sleep-Wake Disorders and Circadian Rhythm Disorders

Which sleep disorder is characterized by a persistent or recurrent pattern of sleep disruption leading to excessive sleepiness or insomnia that is due to a mismatch between the endogenous circadian rhythm and the external environment?

  1. Circadian rhythm sleep-wake disorder Correct answer.
  2. REM sleep behavior disorder
  3. Restless legs syndrome
  4. Central sleep apnea

Explanation

Circadian rhythm sleep-wake disorders are defined by a misalignment between the endogenous circadian timing system and the required or desired sleep-wake schedule, producing insomnia or excessive sleepiness. The other options are respiratory, parasomnia, or movement disorders without this defining circadian misalignment.

Question 35Sleep-Wake Disorders and Circadian Rhythm Disorders

A patient with narcolepsy type 1 is being evaluated. Which finding would most strongly support the diagnosis?

  1. Elevated serum melatonin during the day
  2. Increased REM latency on polysomnography
  3. Cerebrospinal fluid hypocretin-1 level below 110 pg/mL Correct answer.
  4. Cerebrospinal fluid hypocretin-1 level of 50 pg/mL

Explanation

A cerebrospinal fluid hypocretin-1 concentration below 110 pg/mL is a diagnostic criterion for narcolepsy type 1, reflecting loss of hypocretin-producing neurons. Normal values are substantially higher, and increased REM latency is opposite to the expected finding.

Question 36Sleep-Wake Disorders and Circadian Rhythm Disorders

Which of the following is the recommended first-line behavioral treatment for chronic insomnia disorder?

  1. Sleep extension therapy
  2. Long-term benzodiazepine therapy
  3. Paradoxical intention alone
  4. Cognitive behavioral therapy for insomnia Correct answer.

Explanation

Cognitive behavioral therapy for insomnia is recommended as first-line treatment for chronic insomnia because it produces durable improvements without the risks of pharmacotherapy. It combines stimulus control, sleep restriction, cognitive restructuring, and relaxation training. Long-term benzodiazepines carry dependence risk and are not first-line.

Question 37Sleep-Wake Disorders and Circadian Rhythm Disorders

A patient reports sleep paralysis, hypnagogic hallucinations, and cataplexy. Which diagnosis is most likely?

  1. Narcolepsy type 1 Correct answer.
  2. Obstructive sleep apnea
  3. Narcolepsy type 2
  4. Idiopathic hypersomnia

Explanation

The combination of cataplexy with sleep paralysis and hypnagogic hallucinations strongly suggests narcolepsy type 1, in which hypocretin deficiency produces REM dissociation symptoms. Cataplexy is the key feature distinguishing type 1 from type 2. Idiopathic hypersomnia and OSA do not produce cataplexy.

Question 38Sleep-Wake Disorders and Circadian Rhythm Disorders

Which circadian rhythm disorder is most commonly seen in adolescents and young adults and is associated with a stable delay of sleep onset and offset?

  1. Shift work disorder
  2. Advanced sleep-wake phase disorder
  3. Delayed sleep-wake phase disorder Correct answer.
  4. Irregular sleep-wake rhythm disorder

Explanation

Delayed sleep-wake phase disorder is characterized by a stable delay in sleep timing relative to the desired schedule and is most common in adolescents and young adults. The sleep phase is consistently late rather than irregular or advanced. Shift work disorder requires a work-schedule relationship.

Question 39Sleep-Wake Disorders and Circadian Rhythm Disorders

A patient with suspected narcolepsy undergoes a multiple sleep latency test. Which result best supports the diagnosis?

  1. Mean sleep latency of 15 minutes with one sleep-onset REM period
  2. Mean sleep latency of 20 minutes with no sleep-onset REM periods
  3. Mean sleep latency of 6 minutes with two sleep-onset REM periods Correct answer.
  4. Mean sleep latency of 12 minutes with no sleep-onset REM periods

Explanation

A mean sleep latency of 8 minutes or less together with two or more sleep-onset REM periods on the multiple sleep latency test supports a narcolepsy diagnosis. Shorter latency alone or isolated REM onsets are insufficient, and normal latency argues against narcolepsy.

Question 40Sleep-Wake Disorders and Circadian Rhythm Disorders

Which statement about the effect of light on circadian phase is correct?

  1. Light has no effect on circadian phase in humans
  2. Light exposure in the middle of the day produces the largest phase shifts
  3. Light exposure in the late night and early morning produces phase advances Correct answer.
  4. Light exposure in the late evening produces phase advances

Explanation

The phase response curve to light shows that light in the late night and early morning advances the clock, whereas light in the late evening delays it. Light near the middle of the day produces minimal phase shifting. This principle underlies timed light therapy.

Question 41Sleep-Wake Disorders and Circadian Rhythm Disorders

A patient with advanced sleep-wake phase disorder wants to shift sleep later. Which approach is most appropriate?

  1. Morning melatonin administration
  2. Sleep restriction to four hours per night
  3. Morning bright light exposure
  4. Evening bright light exposure Correct answer.

Explanation

In advanced sleep-wake phase disorder the goal is to delay the phase, which is achieved with evening bright light exposure (and morning avoidance of light). Evening light produces phase delays. Morning light and morning melatonin would further advance the clock.

Question 42Sleep-Wake Disorders and Circadian Rhythm Disorders

Which of the following best describes the role of the retinohypothalamic tract in circadian regulation?

  1. It regulates REM sleep muscle atonia
  2. It transmits light information from retinal ganglion cells to the suprachiasmatic nucleus Correct answer.
  3. It transmits motor signals from the cortex to the pineal gland
  4. It carries auditory input to the thalamus

Explanation

The retinohypothalamic tract carries photic information from intrinsically photosensitive retinal ganglion cells to the suprachiasmatic nucleus, allowing light to entrain the master clock. It is not a motor, auditory, or REM-related pathway.

Question 43Sleep-Wake Disorders and Circadian Rhythm Disorders

A patient who works rotating shifts reports insomnia and sleepiness. Which factor most strongly supports a diagnosis of shift work disorder rather than another insomnia disorder?

  1. Symptoms are temporally associated with the shift schedule Correct answer.
  2. The patient has a family history of insomnia
  3. Symptoms persist for at least six months regardless of schedule
  4. Polysomnography shows reduced slow-wave sleep

Explanation

Shift work disorder requires that the insomnia and/or excessive sleepiness be temporally associated with a work schedule that overlaps the habitual sleep period. Symptoms that persist independent of the schedule or nonspecific polysomnographic findings do not establish the diagnosis.

Question 44Sleep-Wake Disorders and Circadian Rhythm Disorders

Which medication is approved for the treatment of cataplexy in narcolepsy?

  1. Modafinil
  2. Sodium oxybate Correct answer.
  3. Zolpidem
  4. Melatonin

Explanation

Sodium oxybate is approved for cataplexy and excessive daytime sleepiness in narcolepsy. Modafinil treats sleepiness but not cataplexy, and zolpidem and melatonin are not cataplexy treatments.

Question 45Sleep-Wake Disorders and Circadian Rhythm Disorders

A patient reports excessive daytime sleepiness with long unrefreshing naps and no cataplexy. Multiple sleep latency test shows a mean sleep latency of 5 minutes but no sleep-onset REM periods, and hypocretin is normal. Which diagnosis is most likely?

  1. Insufficient sleep syndrome
  2. Narcolepsy type 2
  3. Narcolepsy type 1
  4. Idiopathic hypersomnia Correct answer.

Explanation

Idiopathic hypersomnia presents with excessive sleepiness, long unrefreshing naps, a short mean sleep latency, fewer than two sleep-onset REM periods, and normal hypocretin. The absence of cataplexy and REM onsets argues against narcolepsy, and insufficient sleep syndrome would be excluded by adequate sleep duration.

Question 46Sleep-Wake Disorders and Circadian Rhythm Disorders

Which circadian rhythm disorder is characterized by sleep and wake episodes that are fragmented and variable across the 24-hour day, often in patients with neurodegenerative disease?

  1. Irregular sleep-wake rhythm disorder Correct answer.
  2. Delayed sleep-wake phase disorder
  3. Advanced sleep-wake phase disorder
  4. Jet lag disorder

Explanation

Irregular sleep-wake rhythm disorder is marked by a lack of a clear circadian sleep-wake pattern, with fragmented sleep and wake bouts distributed across the day and night. It is common in neurodegenerative conditions such as Alzheimer disease. The phase disorders have a consistent but shifted timing, and jet lag follows travel.

Question 47Sleep-Wake Disorders and Circadian Rhythm Disorders

A patient with narcolepsy type 2 has a mean sleep latency of 6 minutes with two sleep-onset REM periods but no cataplexy and normal hypocretin. Which feature distinguishes type 2 from type 1 in this case?

  1. Presence of sleep-onset REM periods
  2. Mean sleep latency below 8 minutes
  3. Excessive daytime sleepiness
  4. Absence of cataplexy with normal hypocretin Correct answer.

Explanation

Narcolepsy type 2 is distinguished from type 1 by the absence of cataplexy and normal cerebrospinal fluid hypocretin levels, while both share sleepiness and REM-onset findings. Sleep-onset REM periods, short sleep latency, and sleepiness occur in both types and do not differentiate them.

Question 48Sleep-Wake Disorders and Circadian Rhythm Disorders

Which of the following is a key diagnostic criterion for delayed sleep-wake phase disorder?

  1. A significant delay in sleep onset and offset relative to the desired schedule Correct answer.
  2. A mean sleep latency below 8 minutes on testing
  3. Frequent apneas during sleep
  4. Presence of cataplexy

Explanation

Delayed sleep-wake phase disorder is diagnosed when there is a significant and stable delay in the timing of sleep onset and offset relative to the desired or required schedule, with resulting insomnia or sleepiness. Short sleep latency, cataplexy, and apneas are features of other disorders.

Question 49Sleep-Wake Disorders and Circadian Rhythm Disorders

A patient with non-24-hour sleep-wake rhythm disorder who is blind is being considered for treatment. Which intervention is most appropriate?

  1. Morning bright light therapy
  2. Evening bright light therapy
  3. Sleep restriction therapy
  4. Timed melatonin administration Correct answer.

Explanation

In blind individuals without light perception, exogenous melatonin given at a consistent time can entrain the circadian system and is the mainstay of treatment. Light therapy is ineffective without light perception, and sleep restriction does not address the free-running rhythm.

Question 50Sleep-Wake Disorders and Circadian Rhythm Disorders

Which statement about the relationship between circadian phase and core body temperature is correct?

  1. Core body temperature peaks at the time of habitual sleep onset
  2. Core body temperature is constant across the 24-hour day
  3. Core body temperature reaches its minimum in the early morning hours before habitual wake time Correct answer.
  4. Core body temperature reaches its minimum in the late evening

Explanation

The circadian rhythm of core body temperature reaches its nadir in the early morning, typically a few hours before habitual wake time, and this nadir is a useful phase marker. Temperature is not constant, and the peak occurs in the late afternoon or early evening rather than at sleep onset.