This is why you prop up your head when you sleep, otherwise lying at the back would just favour mucus to. All you need is boiling water, a bowl, and a towel. A way to clear the sinuses and avoid and stop sinus issues such as:
Lean Forward Over The Sink With The Head Facing Down Into The Sink.
Mucus is a substance normally produced by the body. You can also use a neti pot once or twice a day, including before bed, to clear. Allow the solution to run into the nasal passage while blocking.