Brett McKay is making a sweeping argument here: cold showers are not a modern wellness trend but a rediscovery. Greeks, Romans, Russians, Japanese Shinto practitioners, Finnish sauna-goers — they all understood something that we collectively forgot when we installed hot water on demand. The claim is that a few minutes of cold water each day delivers cascading benefits across mood, immunity, recovery, fertility, and energy.
That's a large claim. Let me tell you where the science supports it, and where to hold your expectations a little more loosely.
The mood and noradrenaline connection is the most robust piece here. The Virginia Commonwealth research on cold showers stimulating the locus coeruleus — the brain's primary noradrenaline source — holds up well across multiple studies in our knowledge base. We have articles from Huberman, Rhonda Patrick, and independent researchers all converging on the same mechanism: cold exposure triggers a sympathetic nervous system cascade that elevates norepinephrine, often dramatically. This is real, this is measurable, and it's probably the most well-supported benefit of all.
The immunity data is more nuanced. The Thrombosis Research Institute study showing increased white blood cell counts in cold shower takers is genuine, but the effect size is modest and the mechanism — elevated metabolic rate activating immune cells — is indirect. It's not that cold showers are an immune panacea. It's that the hormetic stress response, used consistently, trains your immune system to be slightly more reactive. Small dose, real effect.
The fertility statistic — a 491 percent increase in sperm count — is the most sensational claim in this piece, and it deserves scrutiny. That figure comes from a relatively small study on men who had been using laptops on their laps or taking hot baths regularly. Removing that heat exposure produced dramatic improvements. The implication that cold showers cause this effect is a leap. Removing a harmful habit is not the same as adding a beneficial one. Still worth knowing. Still worth acting on. Just worth framing correctly.
Start at the end of your existing shower. Thirty seconds of cold to finish. Work up to two minutes over two weeks. What you're training is not cold tolerance — it's the decision-making muscle. The moment before you turn that dial is where all the benefit lives. Every time you choose discomfort deliberately, you are practicing agency over your nervous system. That skill transfers.
What strikes me, reading this alongside everything else in our knowledge base, is that the Finns were already doing the complete protocol. Sauna — intense heat stress — followed immediately by a cold lake or snow bank. They didn't need Huberman to explain the contrast effect. They built it into their culture as ritual. The contrast between extreme heat and cold produces a noradrenaline spike that neither stimulus achieves alone. Cold showers are a single instrument. Contrast therapy is the full orchestra. If cold showers are your entry point, welcome. But know that you're only hearing the opening note.