I also get this. With my first it started around 8 weeks. And lasted till I gave birth :/ I'm currenlty 19 weeks and have had it for a month or so now!
Get a humidifier it has totally been my best friend in helping me sleep
I've had this issue since around 9 weeks. I'm 27 weeks 5 days today. Unfortunately it isn't mucus with me, I have looked up my nose with a flashlight and can see my membranes so swollen they completely close off my nasal passages. I use Afrin because it is the only thing that works and I need to sleep.
Saline spray. I been having extra mucus in my throat, tends to get worst at night