I've done 3 Saunas in the past month. Each about an hour. The last one, per my Naturopath's advice, I immediately rinsed off in the shower at the gym to rinse everything off.
I've noticed that they do have benefit and seem to hit area's chelation hasn't helped much with. i.e. the sinus and the eye's.
I'm definately better now, because the first Sauna took almost 30 minutes for me to start sweating. The last one I did, I started sweating after about 10 min and sweat was pouring off me at the 45 min mark. To me that's an indication that my body is handling heat better and my ciculation has improved.