How come I wake up with a snotty nose every morning?

Several reasons. Depends what you mean by snotty. If you mean lots of dried snot, the nose is drying out. If you mean lots of secretions, could be responding to something in the air. If dry, humidify air. If liquid, get air filter.
Possible reasons for. A.M. Nasal congestion include: if you sleep lying flat in bed, this gives mucus a chance to pool in your nasal passages. While you are sleeping the mucus thickens & you wake with congestion. If the air is dry in your home this can contribute to thickening of the mucus. Are you allergic to dust mites? They infest your pillows, mattress and bed linens leading to allergic reactions in some people.