Do sauna cause wrinkles

No sweat does not cause wrinkles.

Although if you sweat so much that your entire body becomes dehydrated, your skin will be dehydrated as well. Dehydration of the body is not healthy at all, so hopefully it doesn't happen too often! - but I guess if you are dehydrating yourself several times a day it could end up causing you wrinkles. In that case I think the rest of your body would shut down a long time before you notice the wrinkles though!