The Science
Cold plunge and contrast therapy: how the Nordic hot-cold cycle works
The research on contrast therapy points to brief, cold plunges between sauna rounds, and a chiller tub earns its price over an ice barrel if you plunge daily.
By Adam Bognar, Editor
The Nordic hot-cold cycle pairs each sauna round with a brief cold plunge, and in Finland and Sweden the cold counts as half the ritual. We read the cold research and compared ice barrels with chiller tubs. That research is younger than the sauna literature, and its best-known findings come from winter swimmers. The gear has matured from stock-tank hacks to purpose-built tubs.
The cold research found brown-fat changes in winter swimmers
A 2021 study of young winter swimmers who alternated cold immersion with sauna found enhanced cold-induced thermogenesis and altered brown-fat thermoregulation compared with controls. Their habit was modest, at around 11 minutes of cold exposure a week alongside regular sauna. The adaptation seems to come from brief, repeated plunges into water that's properly cold.
Should you buy an ice barrel or a chiller tub?
An insulated barrel plus ice is the cheapest way in, and you'll manage the temperature with bags of ice. A chiller-driven tub costs more and keeps the water filtered and sanitized at your exact set temperature every day, so you won't make ice runs. If you plunge daily, that consistency makes the habit easier to keep.
Where to buy
Ice Barrel 500. Ice Barrel photography.
See the specifications and priceRun the contrast protocol for two or three rounds
Spend 15 to 20 minutes in the sauna and 1 to 3 minutes in cold water, then rest a few minutes and repeat for two or three rounds. Keep the water cold and each plunge brief. Cold immersion transiently spikes blood pressure, so clear the routine with a doctor first if you've got any cardiovascular condition.
Where to buy
Hear it from the source
How to Use Cold & Heat Exposure to Improve Your Health | Dr. Susanna Søberg
Metabolic researcher Susanna Søberg talks with Andrew Huberman about how deliberate heat and cold shift metabolism, brown fat, hormones and inflammation. She also covers her widely cited contrast-therapy guidance.
Common questions
- Do I need a chiller or is an ice barrel enough?
- An ice barrel is enough, since an insulated barrel plus a few bags of ice reaches 5 to 10°C. A chiller earns its higher price through daily convenience: steady temperature and filtered, sanitized water with no ice runs. Choose by how often you'll plunge.
- How cold and how long should a cold plunge be?
- A cold plunge of roughly 1 to 3 minutes at 5 to 15°C matches the brief, cold exposure the studied protocols used. Start warmer and shorter while you're building tolerance, and never plunge alone.
Sources
- 1.Altered brown fat thermoregulation and enhanced cold-induced thermogenesis in young, healthy, winter-swimming men. Cell Reports Medicine, 2021.
- 2.Benefits and risks of sauna bathing. The American Journal of Medicine, 2001.
- 3.Cardiovascular and Other Health Benefits of Sauna Bathing: A Review of the Evidence. Mayo Clinic Proceedings, 2018.
We review from makers’ documentation, owner reports and published research. How we choose products and write reviews.
