Have you checked what your indoor humidity level is? If your house is relatively new & built tight, usually the result is high indoor humidty, no low. That's because the act of living in the house is constantly putting moisture in the air (cooking, showers, breathing, plants).
From a health standpoint, a relative humidity of between 40% - 60% is the best, but even at the low end (40%) on those cold nights you may have condensation on your windows. If you check recommendations of window manufacturers, the suggested humidity levels are much lowere, some charts I've seen 15% (thats lip craking dry).
My first suggestion is to check yor level. Radio Shack has a inexpensive, and fairly accurate meter for about $50. If your house is running real dry, you may consider if there is anything you can do to tighten it up. lessing the air exchange will increase you humidity and give you the bonus of decreasing you heating bill. I live in the cold upper midwest (cold air is VERY DRY), I don't worry about adding moisture, my concern is getting rid of it!