Back when I lived in the frozen tundra that is Chicago, my building was equipped with old-school heaters. You know, those "steam" registers that get so hot, you could use them as cooking units. The problem with those clickety-clack heaters? While they were "steam" radiators, they actually made the air so dry that I'd wake up parched. My skin was beginning to suffer.
Since I didn't really have room for a humidifier (no, seriously, it was a tiny studio), my friend suggested I put a pot of water on the hotter-than-hot register to bring moisture into the air. You know what? Her makeshift humidifier worked wonders. Not only did my skin improve, but I slept so much better, too.