The ScienceJuly 20267 min read
Cold plunge and the Nordic cycle: the other half of the ritual
Heat opens the tap; cold slams it shut. What the research on deliberate cold and contrast therapy actually shows, and how to choose between an ice barrel and a chiller tub.
Ask any Finn or Swede and the sauna is only half the ritual — the plunge, the lake, the snow is the other half. The research on deliberate cold is younger than the sauna literature, but the contrast-therapy findings are genuinely interesting, and the gear has matured from stock-tank hacks to purpose-built tubs.
What the cold research shows
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. Notably, the studied habit was modest — on the order of 11 minutes of cold exposure a week alongside regular sauna. The adaptation seems to come from repeated brief, genuinely cold exposure, not heroic endurance soaks.
Ice barrel or chiller tub?
An insulated barrel plus ice is the cheapest way in — you'll manage the temperature with bags of ice. A chiller-driven tub costs more but earns it through consistency: filtered, sanitized water at your exact set temperature every day, no ice runs. If you plunge daily, the chiller pays for itself in habit adherence.
Running the contrast protocol
The classic cycle is heat, plunge, rest, repeat: 15–20 minutes in the sauna, 1–3 minutes in cold water, a few minutes of recovery, two or three rounds. Keep the cold genuinely cold and brief rather than long and lukewarm. If you have any cardiovascular condition, clear it with a doctor first — cold immersion transiently spikes blood pressure.
Watch
Hear it from the source
Dr. Susanna SøbergAndrew Huberman
How to Use Cold & Heat Exposure to Improve Your Health | Dr. Susanna Søberg
Metabolic researcher Susanna Søberg joins Huberman for a deep, protocol-rich conversation on how deliberate heat and cold shift metabolism, brown fat, hormones, and inflammation, including her widely cited contrast-therapy guidance.
Common questions
- Do I need a chiller or is an ice barrel enough?
- Ice works fine — an insulated barrel plus a few bags of ice reaches 5–10°C. A chiller earns its higher price through daily convenience: consistent temperature, filtration, and sanitation with no ice runs. Choose based on how often you'll realistically plunge.
- How cold and how long should a cold plunge be?
- The studied protocols used brief, genuinely cold exposure — roughly 1–3 minutes at 5–15°C — rather than long lukewarm soaks. Start warmer and shorter and build tolerance, and never plunge alone.
Sources
- Altered brown fat thermoregulation and enhanced cold-induced thermogenesis in young, healthy, winter-swimming men · Cell Reports Medicine (2021)
- Benefits and risks of sauna bathing · The American Journal of Medicine (2001)
- Cardiovascular and Other Health Benefits of Sauna Bathing: A Review of the Evidence · Mayo Clinic Proceedings (2018)