Sleep stage determines the expression pattern of sleep apneas.

We report on an obese man with sleep stage-dependent apnea. His type of apnea was predominantly central during non-rapid eye movement (NREM) sleep, while it was obstructive during rapid eye movement (REM) sleep. We found significantly more and more severe apneas during REM sleep compared to NREM sleep. His apneas were remarkably reduced by position adjustment, suggesting that upper airway collapse played a key role in the induction of both types of apnea. As his apneic patterns were dependent on the sleep stages, we assumed that the balance between upper airway obstruction and instability of central respiratory control might be important in determining the expression types.