Short read
Jari Laukkanen, Tanjaniina Laukkanen and Setor Kunutsor wrote this narrative review for Mayo Clinic Proceedings in 2018. It rests on a broad literature search in MEDLINE and EMBASE from the start of both databases to 24 February 2018 and includes observational studies as well as randomised and non-randomised controlled trials. It is the most comprehensive medical overview of sauna bathing in this collection.
The review concludes that sauna bathing is associated with a lower risk of vascular disease, neurocognitive disease, lung disease and death from any cause, and with relief in arthritis, headache and infections. As mechanisms, the authors discuss better endothelium-dependent dilation of the blood vessels, lower arterial stiffness, modulation of the autonomic nervous system, more favourable blood lipid profiles and lower systemic blood pressure.
The review is narrative, not systematic, so it does not pool results or rate study quality in a formal way. The authors are also the originators of a large share of the primary studies they summarise. In this field that is hard to avoid, but it is worth keeping in mind.
The review sets out, for the first time, a coherent physiological framework for the epidemiological findings. It is a starting point for checking whether evidence exists on a given question, not a source of new data. The associations it collects are only as strong as the observational studies behind them, and it makes no recommendation for individuals.