Disagree. I switched from a 75 to 100 watt bulb a couple months ago to try to keep the heat up over the winter. Afterwards I noticed an immediate drop in humidity (about 15%). Like I said I didnt change anything other than my bulb and still saw a significant humidity drop within a few hours. Another reason I believe the bulb is to blame is that over night when I shut the bulb off I can easily maintain 40% with no misting.
As far as your humidity problem goes, I'm not sure where you live but I know for me living in the Midwest I have humidity problems over the winter too. I have found that part of this is caused by the dry air produced by having my furnace on. About the only thing I've found successful is to do what Skiploader said: try to maintain the 40% humidity, keep moist moss in the hide boxes and just tough it out till spring.