Op,
I have woken up gasping for breath. I first thought it was obstructive sleep apnea, but a sleep study ruled it out. And saw an ent friend and oropharanx appears normal. I noticed that it occurs after drinking alcohol so now i take a Claritin with my alcohol and have not had problems. But GERD and larygospasm never occurred to me. I think I’ll toss in 2 tums and a Prevacid/Zantac at night when I drink alcohol fir good measure. Thanks for posting this to make me think about my own diagnosis. Physician heal thyself 
Thanks to you Yoho and everyone who posted.
Sleep apnea can have similar symptoms, usually gasping and not laryngospasm. You can have obstructive sleep apnea with a normal BMI. OSA would not be high on my list of differential diagnoses, but something else to think about if GERD isn’t the problem.
I have had this and it is terrifying. Currently I will get it when eating and something goes down the wrong way. One of the worst times was when I bit into a grape and the juice shot into my throat and must have triggered my vocal cords. I thought I would die even though intellectually I know that the muscles relax within a minute usually.
I have often gotten this at night. I will be dreaming that I’m suffocating and then bolt out of bed because my throat feels like it is closed. Sipping warm water and having a cough drop help as does remembering the Bernoulli principle referred to in the link below.
I feel like I must have very sensitive vocal cords or muscles. Even eating normally can trigger the mechanism if food gets too far down my throat before I swallow.
Here is a site I found years ago to explain it
OP - Glad that your doctors did not dismiss this as “no biggie, have a Tums” kind of thing and you are getting checked for all possible causes.
Excellent reference surfcity. Thanks. The comments are also very interesting to read.