Hot, then cold, then hot again. Contrast therapy is the sauna world's favourite party trick, and it's popping up in bathhouses and backyards right across Australia. Here's what it is, what the research does (and doesn't) say, and how to give it a go without shocking your system into next week.
What is contrast therapy (sauna and cold plunge)?
Contrast therapy simply means moving between heat and cold. The classic version is a sauna session followed by a cold plunge, cold shower or bucket of cold water over the head, repeated for a few rounds. The Finns have been doing it for centuries with lakes and snow. Most of us in Australia make do with a plunge tub, an ice bath or a very brisk shower.
Sauna and cold plunge benefits: what the research says
Let's be honest: there's more enthusiasm than evidence for contrast therapy as a combo. But we can look at each half.
Sauna benefits
Regular sauna bathing has been studied quite a bit, mostly in Finland. In one well-known study of 2,315 middle-aged Finnish men followed for about 20 years, men who used a sauna 4 to 7 times a week had a lower risk of fatal cardiovascular events and death from any cause than men who went once a week (Laukkanen et al., JAMA Internal Medicine, 2015). That's observational, so it shows a link, not proof. A later review summarises the wider evidence (Laukkanen et al., Mayo Clinic Proceedings, 2018), and our sauna health benefits research roundup covers it in plain English.
Cold plunge benefits
A meta-analysis of post-exercise cooling found that cold water immersion was associated with less muscle soreness in the days after exercise compared with doing nothing (Hohenauer et al., PLoS One, 2015). Most of those studies were in athletes after hard training, not people having a relaxing Sunday sauna.
Hot and cold together
Good-quality studies on sauna plus cold plunge together, in everyday people, are thin on the ground. Most of what you'll hear about "boosting immunity" or "resetting your nervous system" goes well beyond the evidence. What people reliably report is that it feels fantastic: buzzy, calm and wide awake all at once. We reckon that's reason enough.
Is contrast therapy safe? Cold plunge safety first
Sudden immersion in cold water triggers the "cold shock" response: a gasp, fast breathing and a spike in heart rate. Researchers studying it note it can be dangerous, especially in open water, although the response tends to lessen with repeated exposure (systematic review, Journal of Thermal Biology, 2024).
- Check with your doctor first if you have a heart condition, high or low blood pressure, are pregnant or have any other health concerns.
- Never plunge alone in open water, and never after alcohol.
- Ease in. Walk in slowly, keep your breathing slow and get out if you feel dizzy, numb or panicky.
- Keep it short. Beginners only need seconds, not minutes.
How to do a sauna and cold plunge session
A simple beginner contrast therapy routine
- Warm up in the sauna for 8 to 15 minutes, or until you're nicely heated through. Pop on a wool felt sauna hat so the top bench feels kinder on your head.
- Cool down with a cold shower or plunge for 15 to 60 seconds. Hat off before you dunk.
- Rest for a few minutes at room temperature. Have a big drink of water.
- Repeat 2 to 3 rounds. Many people like to finish on cold, but there's no rule. Finish however feels best.
What to bring to a sauna and cold plunge session
- Swimwear and two towels (one to sit on, one to dry off)
- A 100% wool sauna hat for the hot rounds
- A cork-sleeved Lucky Sauna Water Bottle so you can sip between rounds (see our sauna hydration guide)
- Thongs for the walk between hot and cold
Want somewhere to try it? Plenty of bathhouses now have saunas and plunge pools side by side. Check out our city guides for Brisbane, Sydney and Melbourne.
Sauna and cold plunge: the bottom line
Contrast therapy is a fun, invigorating ritual. The sauna side has some promising long-term research, and cold water can help with post-exercise soreness, but bold claims about the combination are ahead of the science. Go gently, stay hydrated and enjoy the tingle.
Contrast therapy FAQs
How long should you stay in a cold plunge after a sauna?
Beginners can start with 15 to 30 seconds. Some regulars build up to a couple of minutes, but longer isn't necessarily better.
Should you finish on hot or cold?
It's personal preference. Finishing cold feels energising; finishing warm feels cosier. There's no strong evidence either way.
Is contrast therapy safe?
For most healthy adults it's fine done sensibly. If you have a heart condition, blood pressure issues or are pregnant, talk to your doctor first.
Do I wear my sauna hat in the cold plunge?
No. Wear it in the heat and take it off for the plunge. Let it dry between sessions.
This article is general information, not medical advice.