Dry mouth & throat every night from 6 weeks

Claire
Hi ladies,
Just wondering if anyone else is waking up at night with a dry mouth, throat and tongue?! This is my second pregnancy, & I never experienced this with my first. I'm currently 12 weeks, and have had this since about 6 weeks. 
I wake up at various points throughout the night because my mouth is literally bone dry and my throat feels like it's stuck together at the back.
Anybody know what causes this? 
I'll ask my midwife at my next appt in early March. 
Thanks in advance! xx