ABDSM EXAM 2025-2026 | Questions
with Correct Answers | Dental Sleep
Medicine | American Board of Dental
Sleep Medicine | Pass Guaranteed - A+
Graded
[DOMAIN 1: SLEEP PHYSIOLOGY & PATHOPHYSIOLOGY - 38 Questions]
1. Which stage of sleep is characterized by delta waves with amplitude >75 µV and frequency
0.5-2 Hz?
A. N1 (Stage 1)
B. N2 (Stage 2)
C. N3 (Stage 3/Slow-wave sleep)
D. REM sleep
[CORRECT: C] N3 (slow-wave sleep/deep sleep) is characterized by high-amplitude (>75 µV),
low-frequency (0.5-2 Hz) delta waves. This stage represents the deepest non-REM sleep and is
essential for physical restoration, growth hormone release, and memory consolidation.
2. A patient with OSA has a polysomnography showing an AHI of 28 events per hour. According
to standard classification, what is the severity of their OSA?
A. Mild
B. Moderate
C. Severe
D. Cannot be determined from AHI alone
[CORRECT: B] An AHI of 15-30 events per hour indicates moderate OSA. Mild OSA is 5-15,
and severe is >30. The AHI represents the total number of apneas and hypopneas divided by
total sleep time in hours.
3. Which structure is most commonly identified as the primary site of airway collapse in patients
with obstructive sleep apnea?
A. Retroglossal region
B. Retropalatal region
C. Hypopharynx
D. Nasopharynx
[CORRECT: B] The retropalatal region (behind the soft palate) is the most common site of
airway collapse in OSA patients. However, many patients have multiple collapse sites, and the
retroglossal region (behind the base of tongue) is the second most common site.
4. What is the typical duration of a complete sleep cycle in adults?
A. 30-45 minutes
, . 60-75 minutes
B
C. 90-110 minutes
D. 120-150 minutes
[CORRECT: C] A complete sleep cycle typically lasts 90-110 minutes in adults. Most adults
experience 4-6 complete cycles per night, with early cycles containing more N3 (slow-wave)
sleep and later cycles containing more REM sleep.
5. Which of the following best describes critical closing pressure (Pcrit) in the context of OSA
pathophysiology?
A. The pressure at which the airway opens during inspiration
B. The pressure at which the pharyngeal airway collapses
C. The maximum pressure generated by pharyngeal dilator muscles
D. The pressure differential between intrathoracic and atmospheric pressure
[CORRECT: B] Critical closing pressure (Pcrit) is the intraluminal pressure at which the
pharyngeal airway collapses. In OSA patients, Pcrit is elevated (closer to atmospheric
pressure), meaning the airway collapses at higher pressures compared to normal individuals.
6. During REM sleep, which physiological characteristic is most prominent?
A. Increased muscle tone throughout the body
B. Muscle atonia (loss of muscle tone) in postural muscles
C. Decreased brain metabolic activity
D. Absence of dreaming
[CORRECT: B] REM sleep is characterized by muscle atonia (loss of muscle tone) in postural
muscles, mediated by inhibition of spinal motor neurons. This prevents acting out dreams. The
brain is highly active during REM, and dreaming is common.
7. Which of the following is NOT a modifiable risk factor for obstructive sleep apnea?
A. Obesity
B. Alcohol consumption
C. Male gender
D. Smoking
[CORRECT: C] Male gender is a non-modifiable risk factor for OSA. Modifiable risk factors
include obesity, alcohol/sedative use, smoking, supine sleep position, and nasal congestion.
Non-modifiable factors include male gender, age, family history, craniofacial anatomy, and
menopause.
8. In a normal sleep architecture pattern, which statement is accurate regarding slow-wave
sleep (N3)?
A. It is evenly distributed throughout the night
B. It predominates in the first third of the night
C. It increases in duration with each successive sleep cycle
D. It comprises 40-50% of total sleep time in adults
[CORRECT: B] Slow-wave sleep (N3) occurs predominantly during the first third of the night.
This is when growth hormone is primarily secreted. N3 typically comprises 15-25% of total sleep
time in young adults but decreases with age.
9. Which cardiovascular condition has the strongest established association with obstructive
sleep apnea?
A. Atrial fibrillation
, . Systemic hypertension
B
C. Coronary artery disease
D. Heart failure
[CORRECT: B] Systemic hypertension has the strongest and most well-established association
with OSA. The repetitive arousals, hypoxemia, and negative intrathoracic pressure changes
activate sympathetic nervous system, leading to sustained hypertension.
10. What percentage of total sleep time is typically occupied by REM sleep in healthy adults?
A. 5-10%
B. 15-20%
C. 20-25%
D. 30-35%
[CORRECT: C] REM sleep typically comprises 20-25% of total sleep time in healthy adults.
REM periods lengthen with each successive sleep cycle, with the longest REM periods
occurring in the early morning hours.
11. Which pharyngeal dilator muscle is primarily responsible for maintaining airway patency and
is most affected by mandibular advancement devices?
A. Stylopharyngeus
B. Genioglossus
C. Tensor veli palatini
D. Middle pharyngeal constrictor
[CORRECT: B] The genioglossus is the primary pharyngeal dilator muscle responsible for
maintaining airway patency. It protrudes the tongue forward. Mandibular advancement devices
stretch the genioglossus muscle, increasing pharyngeal airway dimensions.
12. Which of the following craniofacial features is most strongly associated with increased risk of
obstructive sleep apnea?
A. Prognathic mandible
B. Retrognathic mandible
C. High mandibular plane angle
D. Wide intermolar distance
[CORRECT: B] Retrognathia (retruded mandible) is strongly associated with OSA risk as it
positions the tongue and soft tissues posteriorly, reducing the pharyngeal airway space. This
anatomical configuration increases airway collapsibility.
13. What is the primary mechanism by which obesity contributes to obstructive sleep apnea?
A. Increased metabolic rate during sleep
B. Fat deposition in pharyngeal tissues reducing airway caliber
C. Decreased respiratory drive
D. Enhanced upper airway muscle tone
[CORRECT: B] Obesity contributes to OSA primarily through fat deposition in pharyngeal
tissues and surrounding structures, reducing airway caliber and increasing tissue collapsibility.
Central obesity also reduces functional residual capacity and lung volume.
14. During which sleep stage are respiratory events typically most severe in patients with
positional OSA?
A. N1 (light sleep)
B. N2
, . N3 (slow-wave sleep)
C
D. REM sleep
[CORRECT: D] In REM sleep, muscle atonia affects the pharyngeal dilator muscles, making the
airway more vulnerable to collapse. However, for positional OSA specifically, events are typically
most severe in the supine position regardless of stage, though REM-related hypotonia can
exacerbate this.
15. What is the primary consequence of intermittent hypoxemia in OSA patients?
A. Decreased sympathetic nervous system activity
B. Sympathetic activation and systemic inflammation
C. Increased parasympathetic tone
D. Enhanced baroreceptor sensitivity
[CORRECT: B] Intermittent hypoxemia in OSA leads to sympathetic activation and systemic
inflammation through mechanisms involving oxidative stress, activation of inflammatory
pathways, and chemoreflex stimulation. This contributes to cardiovascular morbidity.
16. Which of the following best describes the pathophysiology of upper airway collapse during
sleep in OSA?
A. Increased pharyngeal dilator muscle activity exceeding negative intraluminal pressure
B. Negative intraluminal pressure exceeding the ability of dilator muscles to maintain patency
C. Absence of respiratory effort during sleep
D. Excessive positive airway pressure
[CORRECT: B] Upper airway collapse occurs when negative intraluminal pressure generated by
inspiratory effort exceeds the ability of pharyngeal dilator muscles to maintain airway patency.
During sleep, muscle tone decreases, making this balance more precarious.
17. Which metabolic condition is most commonly associated with obstructive sleep apnea?
A. Type 1 diabetes mellitus
B. Type 2 diabetes mellitus
C. Hyperthyroidism
D. Addison's disease
[CORRECT: B] Type 2 diabetes mellitus is strongly associated with OSA through mechanisms
involving insulin resistance, sympathetic activation, inflammation, and hypoxia. The relationship
is bidirectional, with each condition worsening the other.
18. What happens to the prevalence of obstructive sleep apnea with advancing age?
A. Decreases significantly after age 65
B. Remains stable throughout adulthood
C. Increases progressively with age
D. Peaks at age 40-50 then declines
[CORRECT: C] The prevalence of OSA increases progressively with age in both men and
women, though the rate of increase slows in elderly populations. Changes in airway anatomy,
muscle tone, and fat distribution contribute to this increased risk.
19. Which of the following is characteristic of N2 sleep?
A. Delta waves (>75 µV, 0.5-2 Hz)
B. Sleep spindles and K-complexes
C. Sawtooth waves and rapid eye movements
D. Vertex sharp waves and theta activity
with Correct Answers | Dental Sleep
Medicine | American Board of Dental
Sleep Medicine | Pass Guaranteed - A+
Graded
[DOMAIN 1: SLEEP PHYSIOLOGY & PATHOPHYSIOLOGY - 38 Questions]
1. Which stage of sleep is characterized by delta waves with amplitude >75 µV and frequency
0.5-2 Hz?
A. N1 (Stage 1)
B. N2 (Stage 2)
C. N3 (Stage 3/Slow-wave sleep)
D. REM sleep
[CORRECT: C] N3 (slow-wave sleep/deep sleep) is characterized by high-amplitude (>75 µV),
low-frequency (0.5-2 Hz) delta waves. This stage represents the deepest non-REM sleep and is
essential for physical restoration, growth hormone release, and memory consolidation.
2. A patient with OSA has a polysomnography showing an AHI of 28 events per hour. According
to standard classification, what is the severity of their OSA?
A. Mild
B. Moderate
C. Severe
D. Cannot be determined from AHI alone
[CORRECT: B] An AHI of 15-30 events per hour indicates moderate OSA. Mild OSA is 5-15,
and severe is >30. The AHI represents the total number of apneas and hypopneas divided by
total sleep time in hours.
3. Which structure is most commonly identified as the primary site of airway collapse in patients
with obstructive sleep apnea?
A. Retroglossal region
B. Retropalatal region
C. Hypopharynx
D. Nasopharynx
[CORRECT: B] The retropalatal region (behind the soft palate) is the most common site of
airway collapse in OSA patients. However, many patients have multiple collapse sites, and the
retroglossal region (behind the base of tongue) is the second most common site.
4. What is the typical duration of a complete sleep cycle in adults?
A. 30-45 minutes
, . 60-75 minutes
B
C. 90-110 minutes
D. 120-150 minutes
[CORRECT: C] A complete sleep cycle typically lasts 90-110 minutes in adults. Most adults
experience 4-6 complete cycles per night, with early cycles containing more N3 (slow-wave)
sleep and later cycles containing more REM sleep.
5. Which of the following best describes critical closing pressure (Pcrit) in the context of OSA
pathophysiology?
A. The pressure at which the airway opens during inspiration
B. The pressure at which the pharyngeal airway collapses
C. The maximum pressure generated by pharyngeal dilator muscles
D. The pressure differential between intrathoracic and atmospheric pressure
[CORRECT: B] Critical closing pressure (Pcrit) is the intraluminal pressure at which the
pharyngeal airway collapses. In OSA patients, Pcrit is elevated (closer to atmospheric
pressure), meaning the airway collapses at higher pressures compared to normal individuals.
6. During REM sleep, which physiological characteristic is most prominent?
A. Increased muscle tone throughout the body
B. Muscle atonia (loss of muscle tone) in postural muscles
C. Decreased brain metabolic activity
D. Absence of dreaming
[CORRECT: B] REM sleep is characterized by muscle atonia (loss of muscle tone) in postural
muscles, mediated by inhibition of spinal motor neurons. This prevents acting out dreams. The
brain is highly active during REM, and dreaming is common.
7. Which of the following is NOT a modifiable risk factor for obstructive sleep apnea?
A. Obesity
B. Alcohol consumption
C. Male gender
D. Smoking
[CORRECT: C] Male gender is a non-modifiable risk factor for OSA. Modifiable risk factors
include obesity, alcohol/sedative use, smoking, supine sleep position, and nasal congestion.
Non-modifiable factors include male gender, age, family history, craniofacial anatomy, and
menopause.
8. In a normal sleep architecture pattern, which statement is accurate regarding slow-wave
sleep (N3)?
A. It is evenly distributed throughout the night
B. It predominates in the first third of the night
C. It increases in duration with each successive sleep cycle
D. It comprises 40-50% of total sleep time in adults
[CORRECT: B] Slow-wave sleep (N3) occurs predominantly during the first third of the night.
This is when growth hormone is primarily secreted. N3 typically comprises 15-25% of total sleep
time in young adults but decreases with age.
9. Which cardiovascular condition has the strongest established association with obstructive
sleep apnea?
A. Atrial fibrillation
, . Systemic hypertension
B
C. Coronary artery disease
D. Heart failure
[CORRECT: B] Systemic hypertension has the strongest and most well-established association
with OSA. The repetitive arousals, hypoxemia, and negative intrathoracic pressure changes
activate sympathetic nervous system, leading to sustained hypertension.
10. What percentage of total sleep time is typically occupied by REM sleep in healthy adults?
A. 5-10%
B. 15-20%
C. 20-25%
D. 30-35%
[CORRECT: C] REM sleep typically comprises 20-25% of total sleep time in healthy adults.
REM periods lengthen with each successive sleep cycle, with the longest REM periods
occurring in the early morning hours.
11. Which pharyngeal dilator muscle is primarily responsible for maintaining airway patency and
is most affected by mandibular advancement devices?
A. Stylopharyngeus
B. Genioglossus
C. Tensor veli palatini
D. Middle pharyngeal constrictor
[CORRECT: B] The genioglossus is the primary pharyngeal dilator muscle responsible for
maintaining airway patency. It protrudes the tongue forward. Mandibular advancement devices
stretch the genioglossus muscle, increasing pharyngeal airway dimensions.
12. Which of the following craniofacial features is most strongly associated with increased risk of
obstructive sleep apnea?
A. Prognathic mandible
B. Retrognathic mandible
C. High mandibular plane angle
D. Wide intermolar distance
[CORRECT: B] Retrognathia (retruded mandible) is strongly associated with OSA risk as it
positions the tongue and soft tissues posteriorly, reducing the pharyngeal airway space. This
anatomical configuration increases airway collapsibility.
13. What is the primary mechanism by which obesity contributes to obstructive sleep apnea?
A. Increased metabolic rate during sleep
B. Fat deposition in pharyngeal tissues reducing airway caliber
C. Decreased respiratory drive
D. Enhanced upper airway muscle tone
[CORRECT: B] Obesity contributes to OSA primarily through fat deposition in pharyngeal
tissues and surrounding structures, reducing airway caliber and increasing tissue collapsibility.
Central obesity also reduces functional residual capacity and lung volume.
14. During which sleep stage are respiratory events typically most severe in patients with
positional OSA?
A. N1 (light sleep)
B. N2
, . N3 (slow-wave sleep)
C
D. REM sleep
[CORRECT: D] In REM sleep, muscle atonia affects the pharyngeal dilator muscles, making the
airway more vulnerable to collapse. However, for positional OSA specifically, events are typically
most severe in the supine position regardless of stage, though REM-related hypotonia can
exacerbate this.
15. What is the primary consequence of intermittent hypoxemia in OSA patients?
A. Decreased sympathetic nervous system activity
B. Sympathetic activation and systemic inflammation
C. Increased parasympathetic tone
D. Enhanced baroreceptor sensitivity
[CORRECT: B] Intermittent hypoxemia in OSA leads to sympathetic activation and systemic
inflammation through mechanisms involving oxidative stress, activation of inflammatory
pathways, and chemoreflex stimulation. This contributes to cardiovascular morbidity.
16. Which of the following best describes the pathophysiology of upper airway collapse during
sleep in OSA?
A. Increased pharyngeal dilator muscle activity exceeding negative intraluminal pressure
B. Negative intraluminal pressure exceeding the ability of dilator muscles to maintain patency
C. Absence of respiratory effort during sleep
D. Excessive positive airway pressure
[CORRECT: B] Upper airway collapse occurs when negative intraluminal pressure generated by
inspiratory effort exceeds the ability of pharyngeal dilator muscles to maintain airway patency.
During sleep, muscle tone decreases, making this balance more precarious.
17. Which metabolic condition is most commonly associated with obstructive sleep apnea?
A. Type 1 diabetes mellitus
B. Type 2 diabetes mellitus
C. Hyperthyroidism
D. Addison's disease
[CORRECT: B] Type 2 diabetes mellitus is strongly associated with OSA through mechanisms
involving insulin resistance, sympathetic activation, inflammation, and hypoxia. The relationship
is bidirectional, with each condition worsening the other.
18. What happens to the prevalence of obstructive sleep apnea with advancing age?
A. Decreases significantly after age 65
B. Remains stable throughout adulthood
C. Increases progressively with age
D. Peaks at age 40-50 then declines
[CORRECT: C] The prevalence of OSA increases progressively with age in both men and
women, though the rate of increase slows in elderly populations. Changes in airway anatomy,
muscle tone, and fat distribution contribute to this increased risk.
19. Which of the following is characteristic of N2 sleep?
A. Delta waves (>75 µV, 0.5-2 Hz)
B. Sleep spindles and K-complexes
C. Sawtooth waves and rapid eye movements
D. Vertex sharp waves and theta activity
