Taking the heat. Sauna's popular and there may be health benefits too

Sauna enthusiast Michael Calcagno, second from right, sits inside a clear-walled wood-fired sauna during the Seattle Sauna Festival in November. Sauna use has taken off as a health practice and scientists are studying its benefits.

It's an age old practice that's having a moment right now. But is there anything to the health claims? Scientists say sauna is more than hot air.

(Image credit: Mike Kane for NPR)