A single 30-minute sauna session sends immune cells surging, study finds

A Finnish study found that 30 minutes in a sauna, with a brief cold shower halfway, causes a surge of white blood cells into the bloodstream. Every type measured rose, including neutrophils and lymphocytes, before returning to normal within 30 minutes. Researchers say sauna bathing may temporarily mobilise immune cells from tissues, similar to the boost seen during exercise.