Central sleep apnea can be seen in all of the following sleep stage EXCEPT:

Central sleep apnea can be seen in all of the following sleep stage EXCEPT:

• A. N1
• B. REM
• C. N2
• D. N3 (slow-wave sleep)

Answer: (B)

Central sleep apnea occurs when the brain briefly stops sending signals to breathe, so airflow ceases while there’s little or no respiratory effort. This can happen across the non-REM stages, where brain control of breathing can transiently falter. REM sleep, by contrast, is dominated by marked muscle atonia—including the chest wall and other respiratory muscles—and breathing patterns become irregular with often reduced airflow driven by the atonic state. Because the primary issue in REM is airway collapse from decreased tone rather than a complete loss of neural drive, true central apneas are not typical there. So central sleep apnea is seen in N1, N2, and N3, but not commonly in REM, making REM the exception. If breathing stops with ongoing effort during REM, that would suggest an obstructive or mixed pattern rather than a pure central apnea.

Central sleep apnea occurs when the brain briefly stops sending signals to breathe, so airflow ceases while there’s little or no respiratory effort. This can happen across the non-REM stages, where brain control of breathing can transiently falter. REM sleep, by contrast, is dominated by marked muscle atonia—including the chest wall and other respiratory muscles—and breathing patterns become irregular with often reduced airflow driven by the atonic state. Because the primary issue in REM is airway collapse from decreased tone rather than a complete loss of neural drive, true central apneas are not typical there. So central sleep apnea is seen in N1, N2, and N3, but not commonly in REM, making REM the exception. If breathing stops with ongoing effort during REM, that would suggest an obstructive or mixed pattern rather than a pure central apnea.