FWIW, we have had humidifiers, and I think they helped. The first one just bit the dust because it was a cheap piece of crud, the second one we still have but has developed a leak somewhere that we can't quite find, and it's super hard to clean. We also have a vaporiser, but I only used it once when the bean was sick...it isn't adjustable and the room became like a sauna. Blech.
I'm not sure the problem is just dryness...I don't dust as near often as I should and we have wall to wall carpet, plus an array of books and various electronic equipment (thought not in the bedroom). IS is really sensitive to "stuff" (not sure what stuff, but stuff) that makes you congested. Freya is much the same way, maybe in part through genetics, but also because she's still small and that's just the way little people are made.
I can get snuffly, but it just tends not to bother my sleep as much as the other residents here.