Hi!
I'm from the tropics in Singapore which has high humidity environment and a temperature range of 26 - 33 deg celcius, and even here, a few of my friends that I've talked to use the humidifier.
This is especially useful for those who used to wake up with morning runny noses, or those who go around with a blocked nose.
Among those using the humidifier, majority goes at a setting of 3 for the increased moisture in their air-conditioned bedrooms. I personally wouldn't last 5 minutes without my nose blocking up when using the AutoSet Spirit with integrated humidification.
P.S. I have allergic rhinitis and eczema so I need the cool air, but my nose can't take the temperature and humidity change