Gagging while sleeping?

On occasion I'll wake up from sleep (I presume it happens when I'm just more or less to fall asleep), I'll shoot up coughing and gagging. Sometimes it's mild and other times it's so discouraging that I end up gagging, although I don't throw up.

Last dark I had a bad experience within which I drank water continuously but it took me several minutes to calm down. This with the sole purpose happens every once in a while, and regularly I can go back to sleep soon after.

I thought this be possibly sleep apnea, but I don't consistently feel tired after sleeping (although after last hours of darkness I did), I've been told I don't really snore, don't have sore throats or a headache within the morning.
Answers:    It DEFINITELY sounds like a sleep apnea. There are 2 kinds of apnea. The first is where on earth something in the circuitry in your brain a moment ago 'disconnects' or 'shuts off', causing you to literally, stop breathing. The second is OBSTRUCTIVE sleep apnea, which is what I have. (I've slept beside a CPAP machine for over 14 years, now) What it sounds like, is you hold an excessive amount of flesh in your throat. (sounds corny, doesn't it?) My old kinfolk doctor told me when I was a kid that I have a VERY fleshy palate, probably from years of suffering from sore throats (my parents be heavy smokers). As a result, this 'excess flesh' falls back surrounded by my throat, and causes me to snore, and sometimes, stop breathing. All it may take is for you to sit within a smoky room with friends or co-workers, and your throat overracts by 'swelling up'. I think it's a histimine impulse of some sort. Kind of like someone who is allergic to bee stings, and gets stung. The throat can literally swell shut, cause suffocation. As another example, my sister cannot wear perfumes or use certain aerosol sprays (especially nouns fresheners), because her sinuses will swell shut!! The first thing I would try, is to avoid smokers (I know that's hard), and avoid potential irritants, like aersol sprays and trustworthy chemicals, such as Chlorine bleach or ammonia. If this doesn't help, you may want to see an ENT (Ear, Nose and Throat) MD. He may be able to give a hand, and if nothing else, send you to an overnight clinic or hospital to do a 'sleep study', to determine if you DO enjoy sleep apnea. I know this 'answer' was really lengthy, but I hope it be of help to you.