Vocal chords and sauna

I've noticed my voice pitch has raised quite a bit in the past couple years. I used to have a strong baritone voice, now it is approaching a tenor. The only thing I can correlate might be frequent use of my FIR sauna. After doing some searching I found this advice on voicecouncil.com:

"You’d think that saunas and steam baths would be great for your voice, but instead they cause you to sweat, drying out your body and your vocal cords"

Has anyone else noticed any effects on vocal strength?
I wonder if frequent FIR sessions might be weakening my speaking/singing voice.