I was surprised to learn a few years ago that saunas might actually have significant health benefits.

See the references below from The Journal of the American Medical Association (JAMA), The New England Journal of Medicine (NEJM), and Dr. Patrick who has interviewed the original researcher.

[1] https://media.jamanetwork.com/news-item/sauna-use-associated...

[2] https://www.jwatch.org/fw109897/2015/02/24/sauna-use-linked-...

[3] https://www.foundmyfitness.com/episodes/sauna-heart-presenta...