Page 1 of 59
ABDSM PRACTICE EXAM – 2026 AMERICAN
BOARD OF DENTAL SLEEP MEDICINE —
DIPLOMATE CERTIFICATION COMPLETE (135)
CURRENT TESTING QUESTIONS AND CORRECT
ANSWERS WITH DETAILED RATIONALES.
ABDSM
Prepare for the ABDSM certification with this comprehensive practice
exam designed to reinforce key concepts and support effective exam
preparation. This resource helps you review essential topics, assess your
knowledge, and identify areas that may require additional study. Use it to
strengthen your understanding and build confidence before your
certification exam. An excellent study companion for focused, organized,
and efficient preparation.
MULTIPLE CHOICE.
Section 1: Sleep Physiology & Architecture (Questions 1–15)
1. Which of the following correctly lists the stages of sleep in
order from lightest to deepest?
A. N1, N2, N3, REM
B. REM, N1, N2, N3
C. N1, REM, N2, N3
D. N3, N2, N1, REM
Correct answer: A. N1, N2, N3, REM
Rationale: Sleep progresses through N1 (lightest), N2, N3 (deepest
, Page 2 of 59
slow-wave sleep), and then REM sleep. This cycle repeats
approximately every 90 minutes throughout the night.
2. Which of the following is TRUE regarding REM sleep?
A. REM sleep is characterized by low brain activity
B. REM sleep is when most dreaming occurs
C. REM sleep is the deepest stage of sleep
D. REM sleep is absent in healthy adults
Correct answer: B. REM sleep is when most dreaming occurs
Rationale: REM (Rapid Eye Movement) sleep is characterized by
high brain activity, vivid dreaming, and muscle atonia. It is not the
deepest stage; N3 is the deepest.
3. The suprachiasmatic nucleus (SCN) is primarily responsible
for:
A. Regulating respiratory rate during sleep
B. Controlling the circadian rhythm
C. Initiating REM sleep
D. Regulating muscle tone during sleep
Correct answer: B. Controlling the circadian rhythm
Rationale: The suprachiasmatic nucleus (SCN) located in the
hypothalamus is the body's master circadian clock, regulating the
sleep-wake cycle in response to light cues.
, Page 3 of 59
4. What is the recommended minimum total sleep time for
healthy adults?
A. 5 hours
B. 6 hours
C. 7 hours
D. 9 hours
Correct answer: C. 7 hours
Rationale: The American Academy of Sleep Medicine recommends
that adults obtain at least 7 hours of sleep per night for optimal
health.
5. The hormone primarily responsible for promoting sleep onset
is:
A. Cortisol
B. Melatonin
C. Ghrelin
D. Leptin
Correct answer: B. Melatonin
Rationale: Melatonin is a hormone produced by the pineal gland
that promotes sleep onset and helps regulate the sleep-wake cycle.
Cortisol promotes wakefulness.
6. Which of the following statements about sleep homeostasis is
TRUE?
A. Sleep need decreases throughout the day
B. Sleep pressure (homeostatic drive) increases with time awake
, Page 4 of 59
C. Circadian rhythm is independent of sleep homeostasis
D. Sleep homeostasis is regulated by melatonin alone
Correct answer: B. Sleep pressure (homeostatic drive) increases
with time awake
Rationale: Sleep homeostasis, or sleep pressure, builds up during
wakefulness and dissipates during sleep. The longer one is awake,
the greater the drive to sleep.
7. Muscle atonia during REM sleep is primarily caused by:
A. Increased sympathetic nervous system activity
B. Inhibition of motor neurons in the brainstem
C. Decreased melatonin production
D. Increased cortisol secretion
Correct answer: B. Inhibition of motor neurons in the brainstem
Rationale: During REM sleep, motor neurons are actively inhibited
by brainstem mechanisms, resulting in skeletal muscle paralysis
(atonia) to prevent acting out dreams.
8. Which of the following best describes the "two-process
model" of sleep regulation?
A. REM and NREM sleep alternate in a fixed pattern
B. Sleep is regulated by circadian and homeostatic processes
C. Sleep is regulated solely by light exposure
D. Sleep is regulated by melatonin and cortisol
Correct answer: B. Sleep is regulated by circadian and homeostatic
processes
ABDSM PRACTICE EXAM – 2026 AMERICAN
BOARD OF DENTAL SLEEP MEDICINE —
DIPLOMATE CERTIFICATION COMPLETE (135)
CURRENT TESTING QUESTIONS AND CORRECT
ANSWERS WITH DETAILED RATIONALES.
ABDSM
Prepare for the ABDSM certification with this comprehensive practice
exam designed to reinforce key concepts and support effective exam
preparation. This resource helps you review essential topics, assess your
knowledge, and identify areas that may require additional study. Use it to
strengthen your understanding and build confidence before your
certification exam. An excellent study companion for focused, organized,
and efficient preparation.
MULTIPLE CHOICE.
Section 1: Sleep Physiology & Architecture (Questions 1–15)
1. Which of the following correctly lists the stages of sleep in
order from lightest to deepest?
A. N1, N2, N3, REM
B. REM, N1, N2, N3
C. N1, REM, N2, N3
D. N3, N2, N1, REM
Correct answer: A. N1, N2, N3, REM
Rationale: Sleep progresses through N1 (lightest), N2, N3 (deepest
, Page 2 of 59
slow-wave sleep), and then REM sleep. This cycle repeats
approximately every 90 minutes throughout the night.
2. Which of the following is TRUE regarding REM sleep?
A. REM sleep is characterized by low brain activity
B. REM sleep is when most dreaming occurs
C. REM sleep is the deepest stage of sleep
D. REM sleep is absent in healthy adults
Correct answer: B. REM sleep is when most dreaming occurs
Rationale: REM (Rapid Eye Movement) sleep is characterized by
high brain activity, vivid dreaming, and muscle atonia. It is not the
deepest stage; N3 is the deepest.
3. The suprachiasmatic nucleus (SCN) is primarily responsible
for:
A. Regulating respiratory rate during sleep
B. Controlling the circadian rhythm
C. Initiating REM sleep
D. Regulating muscle tone during sleep
Correct answer: B. Controlling the circadian rhythm
Rationale: The suprachiasmatic nucleus (SCN) located in the
hypothalamus is the body's master circadian clock, regulating the
sleep-wake cycle in response to light cues.
, Page 3 of 59
4. What is the recommended minimum total sleep time for
healthy adults?
A. 5 hours
B. 6 hours
C. 7 hours
D. 9 hours
Correct answer: C. 7 hours
Rationale: The American Academy of Sleep Medicine recommends
that adults obtain at least 7 hours of sleep per night for optimal
health.
5. The hormone primarily responsible for promoting sleep onset
is:
A. Cortisol
B. Melatonin
C. Ghrelin
D. Leptin
Correct answer: B. Melatonin
Rationale: Melatonin is a hormone produced by the pineal gland
that promotes sleep onset and helps regulate the sleep-wake cycle.
Cortisol promotes wakefulness.
6. Which of the following statements about sleep homeostasis is
TRUE?
A. Sleep need decreases throughout the day
B. Sleep pressure (homeostatic drive) increases with time awake
, Page 4 of 59
C. Circadian rhythm is independent of sleep homeostasis
D. Sleep homeostasis is regulated by melatonin alone
Correct answer: B. Sleep pressure (homeostatic drive) increases
with time awake
Rationale: Sleep homeostasis, or sleep pressure, builds up during
wakefulness and dissipates during sleep. The longer one is awake,
the greater the drive to sleep.
7. Muscle atonia during REM sleep is primarily caused by:
A. Increased sympathetic nervous system activity
B. Inhibition of motor neurons in the brainstem
C. Decreased melatonin production
D. Increased cortisol secretion
Correct answer: B. Inhibition of motor neurons in the brainstem
Rationale: During REM sleep, motor neurons are actively inhibited
by brainstem mechanisms, resulting in skeletal muscle paralysis
(atonia) to prevent acting out dreams.
8. Which of the following best describes the "two-process
model" of sleep regulation?
A. REM and NREM sleep alternate in a fixed pattern
B. Sleep is regulated by circadian and homeostatic processes
C. Sleep is regulated solely by light exposure
D. Sleep is regulated by melatonin and cortisol
Correct answer: B. Sleep is regulated by circadian and homeostatic
processes
