I am experiencing the same thing. My fiance complains that I make this noise constantly, but I have no idea that I am even doing it - I am asleep! I cannot recreate the noise for the doctor, so its impossible for me to describe the issue for them. Did you ever find a resolution?
Ive been dealing with the same thing for years. I dont really know why it happens. Although i kinda think its a mental thing. People have told me about it before and ive always calked it up to grinding my teath but after spending hours with my girlfriend trying to recreate the noise, it turns out i suck the back of my throat. Its hard to explain but its like i push my tongue against the roof of my mouth and suck in causing my tongue to vibrant against the back of my throat. I'm really confused because i never make the sound when im awake nor have i ever heard anybody else do so. It only happens while im sleeping. I just started my search for a solution and found nothing so far...seems im a little late to this forum but hopefully someone has found an answer by now or atleast my small insight helps somebody.
This has happened to me all my life and I've heard my brothers do it too. It finally clicked in for me one night when I heard my brother. This is how babies suck; it's this crazy powerful vacuum. It's like part of this primordial survival instinct stays alive in some of us.
I'm thinking about going to operate that hoping it will resolve that. But for example, my father and my sister have the deviation as well but they don't get throat irritated. So I'm not sure if that's the solution.
Your sanity aside, you should really get him to have this remedied as people with undiagnosed sleep apnea run the risk of developing right-sided heart failure (and then left-sided heart failure), or in rare cases, Eisenmenger syndrome.