Basically chronic stress leads to chronic subconscious hyperventilation. It makes perfect sense.
If your nervous system is in fight or flight, it thinks you are about to run or fight, and you cells will produce more CO2 and therefore will need more O2. So your breathing rate and depth increases.
Problem is....with modern day stress, our muscles are not generating CO2. We are just sitting there overbreathing for our level of activity.
If you are sleeping and overbreathing, what happens is your CO2 gets too low, so you stop breathing for a while. Then when your CO2 gets too high, you take a big sudden gasp
I keep plugging it :) But what solved this for me is the Buteyko Breathing Technique. It corrects subconscious breathing by re-training your internal set-point for CO2.
Buteyko corrected much more than sleep problems for me. Hyperventilation is responsible for many of our symptoms since hyperventilation actually starves your cells of oxygen.