I have had a Far Infrared Sauna for over a year and use it almost daily. I get in my sauna at around 120 F and will get it up to 146/151 F, but I've gradually gotten to this temp at a slow pace. I learned early not to force temp like that. Because of time restraints here lately I've been staying in it for only about an hour. When I had now time and was doing it for an hour an half I was seeing much better results such as less muscle tension and just an over all well being. I have a three person sauna so it's easier for me to lay down. If I had to sit up I don't think I could take that much heat for that amount of time and I sweat like crazy so i know I'm getting a lot of toxins out. I do replenish my self every 30 minutes with water spiked with liquid magnesium and potassium. Do a search of vitamins and replenishing your body after using a sauna. It is important.