Sauna and cold plunges have had a huge amount of attention in recent years, and health claims have grown at the same pace. Here we go through what the research actually says – and where it is still uncertain. We sell sauna sessions, so we've been extra careful not to overstate anything.
Sauna: strong links, but not proof
The most-cited research comes from Finland. A large study followed just over 2,300 middle-aged men for around 20 years. Those who took a sauna four to seven times a week had a lower risk of dying from cardiovascular disease than those who went once a week.
That is an association, not proof. People who sauna often may differ in other ways – in lifestyle, health and time to rest. The researchers themselves call for more studies to understand why.
Cold plunges: promising but uncertain
A 2025 systematic review gathered randomised trials on cold-water immersion in healthy adults. It found signs of effects on stress, sleep and quality of life, but also that the studies are few, small and short. The conclusion: more and better research is needed.
Much of what is said about cold plunges on social media – about metabolism, immunity and mood – rests on a few small studies or on personal experience.
The risks are well known
The research is clear about the risks of cold water, though. Cold shock – the rapid breathing and rising heart rate in the first minutes – is a known cause of drowning and can strain the heart. That's why you should get in slowly, never swim alone and be careful with alcohol.
What we know for sure
Many people find that sauna and cold dips make them feel good – they sleep well, feel calm and have fun together. It doesn't need to be proven to be worth it. But it is an experience, not a treatment.
Sources
- Laukkanen et al. (2015): Association between sauna bathing and fatal cardiovascular and all-cause mortality events. JAMA Internal Medicine.
- Cain et al. (2025): Effects of cold-water immersion on health and wellbeing: A systematic review and meta-analysis. PLOS ONE.
- Tipton et al. (2017): Cold water immersion: kill or cure? Experimental Physiology.
