I could not get the link to work. I am extremely concerned about this as i have used my far-infra-red sauna quite a bit. If I have a break and go back to it i feel really bad the first time and I do not sweat much anyway. I feel much better when I am in a dry sunny place as then I do sweat but here in the UK....no. Dr Sarah Myhill advises them most strongly.

Was the person who supplied the rock sauna in London by the way?