Cimorene

Sounds like you're having post-nasal drip while you're asleep and it's irritating your throat. This can be caused by a lot of things (including allergies), but the most common one that requires treatment is a sinus infection.

The best non-antibiotic way to get rid of one, FYI, is to take huge amounts of decongestants and chug water. If you start to see green snot, then congrats - it's a sinus infection.