Sauna and cold plunge, also called contrast therapy, means alternating intense heat with cold water. It's an old practice: Finns have used the sauna for generations, Russians the banya, and many cultures some form of sweat bath, often followed by a dip in a cold lake or snow. Today it's one of the most popular wellness rituals around, and research is starting to catch up.
What research suggests about sauna
In a study that followed more than 2,300 middle-aged Finnish men for about 20 years, those who used the sauna 4 to 7 times a week had a lower rate of fatal heart events and death from any cause than those who went once a week (Laukkanen et al., 2015). It was an observational study in Finnish men, so it shows a link, not proof, but it's one of the most cited studies in the sauna world.
What research suggests about cold plunge
In a 2021 study, Scandinavian men who swam in cold water 2 to 3 times a week and used the sauna showed better body temperature regulation when exposed to cold than men who didn't (Søberg et al., 2021). It was a small study of men only, and much of cold plunging's popularity still comes from personal experience: people often describe feeling alert, energized and calm afterward.
A simple sauna and cold plunge routine
- Hydrate first: water and electrolytes 30 minutes before.
- Sauna: 10 to 20 minutes, leaving sooner if you feel lightheaded.
- Cold plunge: 1 to 3 minutes in cold water, breathing slowly.
- Rest: a few minutes at room temperature.
- Repeat: 2 to 3 rounds, often ending on cold.
- Rehydrate: water and electrolytes after.
Start gently and build up. If you're pregnant, have a heart condition or high blood pressure, or take medication, check with your healthcare provider before using a sauna or cold plunge.
Why electrolytes matter for contrast therapy
Sauna sessions can make you sweat heavily, and sweat isn't just water. It carries sodium, along with smaller amounts of potassium and magnesium. How much sodium varies a lot from person to person, roughly 400 to 1,600mg per liter of sweat in one study of athletes (Gatorade Sports Science Institute). Drinking only plain water after a heavy sweat replaces the fluid but not the minerals, which is why some people feel drained, headachy or crampy after a long session. Learn more in What Are Electrolytes?
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Frequently asked questions
Should you do sauna or cold plunge first?
Most people start with sauna, then cold plunge, and repeat. Many like to end on cold.
How long should you stay in a sauna?
Usually 10 to 20 minutes per round. Leave if you feel dizzy or unwell.
How long should a cold plunge be?
Beginners often start with 30 seconds to a minute and build up to 2 or 3 minutes.
Do you need electrolytes after a sauna?
If you sweat heavily, yes. Sweat carries sodium and other minerals that water alone doesn't replace.
How often should you do sauna and cold plunge?
Many people do it 2 to 4 times a week. In the Finnish study, more frequent sauna use was linked to better outcomes.