Sauna Four Times a Week Could Add Years to Your Life, Science Says

If you’ve been looking for an excuse to spend more time sweating in a hot box, Finnish researchers just handed you one backed by two decades of solid data.

A long-running cohort study published in JAMA Internal Medicine in 2015 tracked 2,315 men over 20 years and found something striking: men who used a sauna four to seven times per week had a 40 percent lower risk of dying from any cause and a 50 percent lower risk of fatal cardiovascular disease compared to those who went just once a week. That’s not a small bump in the health department—it’s the kind of effect size that makes researchers sit up and pay attention. A follow-up in BMC Medicine in 2018 brought women into the picture and found the same pattern held: more sessions per week meant lower cardiovascular mortality risk, with no upper limit on the benefit.

Now, here’s where the honest part comes in. The research shows correlation, not causation. These are observational studies, which means we can’t say sauna use directly caused the health gains. But the dose-dependent relationship—more sessions, better outcomes—is what researchers call a meaningful signal. It’s not just noise.

So what’s actually happening in your body during a sauna session? Heat acts as a controlled stressor that triggers real physiological adaptations. Your heart rate climbs to 100 to 150 beats per minute, plasma volume expands, and heat shock proteins get activated—particularly HSP70, which repairs damaged proteins and reduces systemic inflammation. Over time, regular sauna use is linked to improved endothelial function, lower resting blood pressure, and reduced arterial stiffness. Those changes aren’t just good for your heart; they support healthy blood flow to the brain, which is probably why the same Finnish cohort showed a 66 percent lower risk of dementia and a 65 percent lower risk of Alzheimer’s disease in regular sauna users.

The specifics matter, though. The cardiovascular data comes from traditional Finnish dry saunas running at 80 to 100 degrees Celsius (176 to 212 degrees Fahrenheit). If you’re eyeing an infrared sauna at your gym instead, pause: infrared models typically run at 49 to 65 degrees Celsius (120 to 150 degrees Fahrenheit), and while they do raise core body temperature and trigger sweating, they haven’t been studied for long-term longevity outcomes. The Mayo Clinic’s current guidance, updated in September 2024, describes infrared sauna benefits as preliminary. That doesn’t mean they’re useless for recovery or relaxation—just that you’re extrapolating if you’re banking on the same longevity benefits.

If you’re going to do this, the research suggests four to seven sessions per week is the sweet spot, with sessions running at least 19 minutes. Even two to three sessions weekly still showed a 27 percent lower cardiovascular mortality risk compared to once-weekly use. And don’t skip hydration before and after. One more thing: skip the alcohol around sauna time.

Of course, saunas aren’t for everyone. Pregnant people (especially in the first trimester), anyone with unstable cardiovascular disease, recent stroke, active fever or infection, or alcohol intoxication should stay out. If you’re on diuretics, beta-blockers, or transdermal medication patches, heat increases drug absorption in ways that can shift dosing significantly, so check with your doctor first. Children under 16 and people with uncontrolled high blood pressure should approach cautiously with medical guidance.

The bottom line: if you’ve got access to a traditional sauna and no medical contraindications, the science does genuinely support making it a regular habit. This isn’t a trend that’ll fade once we move on to the next biohacking obsession.