Worst feeling EVER! Scary -- you wake up (always from a deep, deep sleep) and can't breathe. As another poster said, you have to exhale. I let out a scream and then I can start to breathe again. The next thing to deal with is the stomach acid in the throat. And sometimes, soiled pillowcases (yuck!).
KEEP A SUPPLY OF ALKA-SELTZER ON HAND AT ALL TIMES. Two Alka-Seltzers (generic is fine) dissolved in water will reduce the acid, and as you swallow it, the bubbles will help dissipate the stomach acid that clings to the inside of your throat and burns. It works better than water, orange juice or soda. Then, when you're able, give your teeth a good brushing. That will also help get rid of the acid and just generally help you feel better & cleaner.
Awful, awful condition. I sometimes forget and eat popcorn or something less than 3 hours before going to bed, and that will bring it on every time. Beer, pasta and milk are also culprits (which means no warm milk before bedtime, LOL). But eggs, bacon, roast beef, etc. (high protein) in small quantities are safer.
Good luck to all fellow sufferers!