Sauna (Thermal Heat Therapy)

Understand

Overview

Sauna, especially the traditional Finnish dry sauna (80–100°C), is the subject of a growing body of research into cardiovascular health and longevity, based mainly on large observational cohorts from Finland, where regular sauna use is a deeply rooted part of the culture (more than 3 million saunas for a population of roughly 5.5 million).

Thermal heat therapy has gained considerable popularity in the biohacking world in recent years as a non-pharmacological health intervention, often paired with cold plunges as part of so-called contrast therapy. It's worth distinguishing, though, between the solid observational data on regular, long-term sauna use and the more speculative, short-term protocols promoted on social media.

Who can genuinely benefit from sauna, and for whom is it a risk? The strongest data concerns people who are cardiovascularly healthy and use the sauna regularly over the long term (4–7 times a week in the cohort studies) — this was the group that showed the lowest risk of cardiovascular death and the lowest risk of dementia. For physically active people, sauna can additionally support recovery and relaxation, though it doesn't replace cardio training. It isn't, however, a practice that's safe for everyone: people with unstable coronary artery disease, a recent heart attack, uncontrolled hypertension, or who are pregnant should discuss sauna use with a doctor first, and taking diuretics or blood-pressure medication raises the risk of dehydration and hypotension during a session. It's also worth remembering that the data comes mainly from a single population (Finland) with a specific lifestyle, so not every effect necessarily carries over fully to people with a different health and cultural profile.

Where it's found

Sauna originates from Finland and the broader Nordic region, where its use dates back thousands of years — the oldest known saunas were smoke-heated earthen pits (so-called savusauna), used as far back as the Iron Age. In Finnish culture, the sauna has always served not just a hygienic function but also a social and spiritual one — it was even used as a place to give birth and for minor medical treatments.

History of use

Modern scientific interest in sauna grew thanks to large Finnish cohort studies (including KIHD, the Kuopio Ischaemic Heart Disease Risk Factor Study), which have tracked the health of thousands of residents of the Kuopio region since the 1980s, including their sauna habits. It was this cohort that produced the key 2015 and 2017 publications linking sauna frequency to lower cardiovascular risk and dementia, moving sauna from cultural tradition into the realm of lifestyle medicine.