I have had this issue for 60 years. Every 6 or 7 years or so, my breathing essentially stops as I try and fall asleep. After many different diagnoses we finally settled on anxiety as the culprit, although lung infections contributed as well. Apnea has been ruled out once.
I currently am back on Busparon and guaifenesin to try and get back on track. I have xanax as needed til the buspar kicks in. I exercise daily, do deep breathing exercises, and try to live in the now. I also put a little Vicks under my nose.
I've also tried melatonin, NyQuil, and lavender.
Has anyone else had this and is there anything that works for you?