It's not exactly common, but you can have central sleep apnoea instead of obstructive sleep apnoea. Essentially, rather than your airway being blocked, you just

It's not exactly common, but you can have central sleep apnoea instead of obstructive sleep apnoea. Essentially, rather than your airway being blocked, you just stop attempting to breath for a period of time. I was diagnosed with this a few years ago, and IIRC there are multiple possible causes of it.