SLEEP PHYSIOLOGY AND CARDIOPULMONARY
INTERACTIONS EXAM QUESTIONS COMPLETE
WITH 100% VERIFIED ANSWERS
1. During REM sleep, which of the following best describes typical
changes in systemic blood pressure and heart rate?
a) Decreased blood pressure and decreased heart rate
b) Increased blood pressure and increased heart rate ✔
c) Decreased blood pressure and increased heart rate
d) Unchanged blood pressure and irregular heart rate
Explanation: REM sleep is characterized by sympathetic dominance,
phasic surges in blood pressure and heart rate, often exceeding waking
values. This contrasts with non-REM sleep, where parasympathetic tone
lowers both.
2. A patient with untreated obstructive sleep apnea (OSA) shows
nocturnal oxygen desaturation. Which cardiopulmonary consequence is
most directly linked to recurrent desaturation/reoxygenation cycles?
a) Decreased platelet aggregation
b) Increased oxidative stress and systemic inflammation ✔
c) Reduced sympathetic nerve activity
d) Bradycardia during apneic episodes
,Explanation: Intermittent hypoxia triggers reactive oxygen species,
activating NF-κB and inflammatory cytokines (IL-6, TNF-α), promoting
endothelial dysfunction and hypertension.
3. Which sleep stage demonstrates the greatest respiratory variability in
healthy adults, including irregular breathing patterns?
a) N1
b) REM ✔
c) N3
d) N2
Explanation: REM sleep suppresses central respiratory drive and
intercostal muscle tone, leading to erratic tidal volume and frequency.
N3 (slow-wave sleep) is the most regular.
4. During stable N3 sleep, the normal PaCO2 level compared to
wakefulness is:
a) 2–4 mmHg lower
b) 2–4 mmHg higher ✔
c) 5–8 mmHg higher
d) unchanged
Explanation: Reduced alveolar ventilation in N3 due to decreased
respiratory drive and metabolic rate leads to a mild physiologic rise in
PaCO2 (up to ~45 mmHg).
,5. Which cardiac arrhythmia is classically associated with the
bradycardia-tachycardia pattern seen during obstructive apneic events?
a) Atrial fibrillation
b) Sinus arrhythmia with apneic bradycardia and post-apneic
tachycardia ✔
c) Ventricular tachycardia
d) Junctional rhythm
Explanation: During apnea, vagal tone increases → bradycardia; upon
arousal, sympathetic surge → tachycardia. Sinus arrhythmia is typical;
AF may develop chronically.
6. A 55-year-old with severe OSA has a high norepinephrine level upon
waking. This directly contributes to:
a) Increased afterload and left ventricular hypertrophy ✔
b) Decreased systemic vascular resistance
c) Bronchodilation
d) Reduced myocardial oxygen demand
Explanation: Chronic sympathetic activation from OSA raises peripheral
vascular resistance and cardiac afterload, promoting LV hypertrophy
and diastolic dysfunction.
7. In healthy individuals, the lowest minute ventilation during sleep
occurs in:
a) REM sleep
b) N3 sleep ✔
, c) N1 sleep
d) Wake-sleep transition
Explanation: N3 has the deepest central depression of chemoreflexes
and lowest metabolic rate, reducing minute ventilation below REM
levels.
8. Which finding on an echocardiogram is most suggestive of chronic
untreated OSA-induced pulmonary hypertension?
a) Reduced left atrial size
b) Right ventricular hypertrophy and septal flattening ✔
c) Aortic valve sclerosis
d) Pericardial effusion
Explanation: Chronic intermittent hypoxia and large negative
intrathoracic pressures increase right ventricular afterload, causing RV
hypertrophy and diastolic septal flattening.
9. The normal fall in blood pressure during NREM sleep (dipping) is
primarily mediated by:
a) Increased sympathetic outflow
b) Increased parasympathetic tone and decreased sympathetic tone ✔
c) Increased renin-angiotensin activity
d) Increased cortisol release
Explanation: NREM sleep shifts autonomic balance to vagal dominance,
lowering HR and reducing sympathetic vasoconstriction → 10–20% BP
drop.
INTERACTIONS EXAM QUESTIONS COMPLETE
WITH 100% VERIFIED ANSWERS
1. During REM sleep, which of the following best describes typical
changes in systemic blood pressure and heart rate?
a) Decreased blood pressure and decreased heart rate
b) Increased blood pressure and increased heart rate ✔
c) Decreased blood pressure and increased heart rate
d) Unchanged blood pressure and irregular heart rate
Explanation: REM sleep is characterized by sympathetic dominance,
phasic surges in blood pressure and heart rate, often exceeding waking
values. This contrasts with non-REM sleep, where parasympathetic tone
lowers both.
2. A patient with untreated obstructive sleep apnea (OSA) shows
nocturnal oxygen desaturation. Which cardiopulmonary consequence is
most directly linked to recurrent desaturation/reoxygenation cycles?
a) Decreased platelet aggregation
b) Increased oxidative stress and systemic inflammation ✔
c) Reduced sympathetic nerve activity
d) Bradycardia during apneic episodes
,Explanation: Intermittent hypoxia triggers reactive oxygen species,
activating NF-κB and inflammatory cytokines (IL-6, TNF-α), promoting
endothelial dysfunction and hypertension.
3. Which sleep stage demonstrates the greatest respiratory variability in
healthy adults, including irregular breathing patterns?
a) N1
b) REM ✔
c) N3
d) N2
Explanation: REM sleep suppresses central respiratory drive and
intercostal muscle tone, leading to erratic tidal volume and frequency.
N3 (slow-wave sleep) is the most regular.
4. During stable N3 sleep, the normal PaCO2 level compared to
wakefulness is:
a) 2–4 mmHg lower
b) 2–4 mmHg higher ✔
c) 5–8 mmHg higher
d) unchanged
Explanation: Reduced alveolar ventilation in N3 due to decreased
respiratory drive and metabolic rate leads to a mild physiologic rise in
PaCO2 (up to ~45 mmHg).
,5. Which cardiac arrhythmia is classically associated with the
bradycardia-tachycardia pattern seen during obstructive apneic events?
a) Atrial fibrillation
b) Sinus arrhythmia with apneic bradycardia and post-apneic
tachycardia ✔
c) Ventricular tachycardia
d) Junctional rhythm
Explanation: During apnea, vagal tone increases → bradycardia; upon
arousal, sympathetic surge → tachycardia. Sinus arrhythmia is typical;
AF may develop chronically.
6. A 55-year-old with severe OSA has a high norepinephrine level upon
waking. This directly contributes to:
a) Increased afterload and left ventricular hypertrophy ✔
b) Decreased systemic vascular resistance
c) Bronchodilation
d) Reduced myocardial oxygen demand
Explanation: Chronic sympathetic activation from OSA raises peripheral
vascular resistance and cardiac afterload, promoting LV hypertrophy
and diastolic dysfunction.
7. In healthy individuals, the lowest minute ventilation during sleep
occurs in:
a) REM sleep
b) N3 sleep ✔
, c) N1 sleep
d) Wake-sleep transition
Explanation: N3 has the deepest central depression of chemoreflexes
and lowest metabolic rate, reducing minute ventilation below REM
levels.
8. Which finding on an echocardiogram is most suggestive of chronic
untreated OSA-induced pulmonary hypertension?
a) Reduced left atrial size
b) Right ventricular hypertrophy and septal flattening ✔
c) Aortic valve sclerosis
d) Pericardial effusion
Explanation: Chronic intermittent hypoxia and large negative
intrathoracic pressures increase right ventricular afterload, causing RV
hypertrophy and diastolic septal flattening.
9. The normal fall in blood pressure during NREM sleep (dipping) is
primarily mediated by:
a) Increased sympathetic outflow
b) Increased parasympathetic tone and decreased sympathetic tone ✔
c) Increased renin-angiotensin activity
d) Increased cortisol release
Explanation: NREM sleep shifts autonomic balance to vagal dominance,
lowering HR and reducing sympathetic vasoconstriction → 10–20% BP
drop.
