As people drink there are certain common effects; they get clumsy, they get loud. They forget that some things are better kept private. They think EVERYTHING is an AWESOME IDEA. And they eat a takeaway, go to sleep somewhere (hopefully, but not always, indoors) and wake up suffering for it.
But it doesn’t take that much drink to make someone loud and annoying in their sleep.
Alcohol has a lot of different reactions with the body. The most important one to remember is that it dehydrates you – meaning you think you’re drinking plenty but it actually dries you out. This is why you wake up with a mouth like Ghandi’s slipper.
Do you remember picking wide stems of grass as a child and putting them between your thumbs to make whistles? Blowing air past a reed makes a funny noise; it’s the basis of most wind instruments. What alcohol does is dry out the mouth, throat and nasal passages and turn them into the reeds for a giant human oboe.