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

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

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

Answer: (B)

Central sleep apnea reflects a drop in the brain’s drive to breathe, so airflow pauses occur when respiratory effort ceases. This central control instability can show up more readily in non-REM sleep, where ventilatory control is less actively modulated by arousal and feedback loops can destabilize, leading to central pauses in breathing. You can see central apneas during light N1, N2, and even deeper N3 sleep, often in patterns where the brain’s ventilatory drive falls short for a moment. REM sleep behaves differently. It features marked atonia of most skeletal muscles, including those involved in chest wall movement, while the brainstem continues to generate a breathing rhythm. Ventilation is typically maintained by this brainstem drive and diaphragmatic activity despite the muscle atonia, so complete cessation of respiratory effort (the hallmark of a central apnea) is less likely to occur in REM. That’s why central sleep apnea is not typically seen in REM sleep—the stage is the exception rather than the rule.

Central sleep apnea reflects a drop in the brain’s drive to breathe, so airflow pauses occur when respiratory effort ceases. This central control instability can show up more readily in non-REM sleep, where ventilatory control is less actively modulated by arousal and feedback loops can destabilize, leading to central pauses in breathing. You can see central apneas during light N1, N2, and even deeper N3 sleep, often in patterns where the brain’s ventilatory drive falls short for a moment.

REM sleep behaves differently. It features marked atonia of most skeletal muscles, including those involved in chest wall movement, while the brainstem continues to generate a breathing rhythm. Ventilation is typically maintained by this brainstem drive and diaphragmatic activity despite the muscle atonia, so complete cessation of respiratory effort (the hallmark of a central apnea) is less likely to occur in REM. That’s why central sleep apnea is not typically seen in REM sleep—the stage is the exception rather than the rule.