Dr. Susanna Soeberg is making a specific argument here, and it's worth being precise about what it is. Not that cold exposure is good for you — that's too broad. Her claim is more targeted: two to three minutes in uncomfortably cold water, done consistently four to seven times per week, is sufficient to activate brown adipose tissue, stimulate norepinephrine release, and produce meaningful metabolic benefits. The dose is small. The frequency is what matters.
That's a different claim than what you often hear in the broader cold exposure conversation, and it's a more accessible one.
What I find interesting is how Soeberg's work aligns with and diverges from Andrew Huberman's dopamine research on cold exposure. Huberman focuses heavily on the neurochemical cascade — the dopamine and norepinephrine surge that follows cold immersion, which he argues is one of the most reliable mood-elevating tools available. Soeberg's frame is more metabolic: she's watching what happens to brown fat, to glucose uptake, to energy expenditure. Two researchers, two lenses, looking at the same biological event.
The 2019 research on cold-induced changes in brown adipose tissue supports Soeberg's mechanism precisely. That paper documented dynamic shifts in BAT activity during cold exposure — not a binary on/off switch, but a heterogeneous, graded response that varies by individual. Some people have more brown fat. Some respond more strongly. The adaptation is real, but it's not uniform.
There's strong consensus on the norepinephrine response. Cold water hits, the sympathetic nervous system fires, norepinephrine floods the system. That part is well-established across the literature. Where researchers diverge is on optimal temperature, duration, and timing relative to exercise. Soeberg says two to three minutes of uncomfortably cold water. Others argue that exact temperature matters — that 50 to 60 degrees Fahrenheit produces different adaptations than colder water. The honest answer is that the research is still maturing.
Start with what Soeberg actually prescribes: cold enough to be uncomfortable, two to three minutes, four times per week minimum. Don't optimize for heroics. The goal is consistency, not suffering. If you're ending sessions shivering violently for twenty minutes afterward, you've gone too long. The target is a controlled stress response, not depletion.
Here's what strikes me most about Soeberg's framing. She describes the body reacting as if you're going to die — and that's precisely the point. Brown fat is a relic of our evolutionary past, designed to keep infants alive in cold environments. Most adults lose it. Cold exposure is essentially a signal that tells dormant tissue: you're still needed. You're waking up ancestral biology that modern life has put to sleep. That's not a metaphor. That's cellular signaling. And two to three minutes is apparently enough to send it.