"Are there certain strains I can purchase that won’t give me this terrible side effect? I enjoy vaping before bed each night, but I can’t stand the dry mouth that typically follows."
I am not a doctor, but I know that this is a very common experience. It is also one of the only known health hazards of smoking or vaping cannabis over a long period of time. The cotton mouth you refer to actually can lead to gum disease which eventually leads to periodontal disease ie the loss of teeth!
The reason you get the cotton mouth is due to the endocannabinoid system in your body and the series of cannabinoid receptors known as CB1 and CB2 receptors. When you ingest marijuana it binds to both of these receptors which play a part in the production of saliva. Your body is basically being told to stop producing the right amount of saliva as the message becomes blocked, I like to think of it as a numbing agent to the parasympathetic nervous system.
Unfortunately, there is no cure all for cotton mouth. It is suggested that if this effects you often that you drink a lot more water during the day as your body could also be combatting dehydration which is made worse by vaping. Also, it is advised to avoid all things sugary such as sodas or sweets before bed. Some people say that sucking on a hard candy when you get cotton mouth is a great idea, but, I think this is not such a good idea as it’s sugary.
Personally, I find that if i decrease my THC intake to a minimum I do not get cotton mouth. One suggestion would be to try a high CBD strain and see if that relaxes you enough before bed, in lieu of a high THC strain.
I hope this helps!