Dr. Jack Kruse is making a sweeping argument here: that for people living above roughly 60 degrees latitude, the absence of adequate sunlight isn't just an inconvenience — it's a biological crisis. And that the antidote involves two things our modern world has systematically stripped away: natural light and deliberate cold. That's a big claim. Let me tell you where I think he's right, where the science gets slippery, and what this means if you actually live somewhere dark and cold for half the year.
The link between latitude and chronic disease is real and well-documented. Vitamin D deficiency is more prevalent the further you get from the equator. Seasonal affective disorder, metabolic syndrome, cardiovascular risk — all of these correlate with reduced sunlight exposure. The Finnish population studies we reference constantly in the sauna literature come from one of the most light-deprived countries on earth, and yet Finns who use sauna regularly show dramatically lower rates of cardiovascular mortality. That's not a coincidence. Their bodies are compensating through deliberate thermal stress for what the sun isn't providing.
Kruse's point about mitochondrial function and cold exposure has solid ground beneath it. We know from multiple studies — including work featured in our contrast therapy articles — that cold water immersion activates uncoupling proteins in mitochondria, improves insulin sensitivity, and stimulates brown adipose tissue. Dr. Thomas's research goes even further, suggesting that people in chronically dark, cold environments may actually have a metabolic advantage if they lean into the cold rather than insulate against it. Nature's compensation, as he puts it.
Here's where I'd urge some caution. Kruse moves into quantum biology territory that goes well beyond consensus science. Comparing sun avoidance to smoking is provocative — and while the sentiment has merit, the mechanisms he proposes around water depletion and light absorption are not yet peer-reviewed in the way his confidence implies. Take the framework as a useful lens, not a completed theory. The sunlight and cold parts are solid. The quantum water chemistry is speculative.
If you live at high latitude, the actionable message is clear regardless of where you land on quantum biology: catch the sunrise when you can. Even five minutes of morning light, even through cloud cover, is signaling your circadian system. Add deliberate cold — three times a week, even a two-minute cold shower counts — and you're activating the same metabolic pathways that cold plunging or ice bathing would. The dose doesn't need to be heroic. It needs to be consistent.
What strikes me most is this: Wim Hof himself grew up in the Netherlands, one of the cloudiest, greyest places in northern Europe. He didn't move somewhere sunnier. He went deeper into the cold. That instinct — to meet the environment on its terms rather than insulate against it — runs through everything we've built this knowledge base around. Contrast therapy isn't about escaping discomfort. It's about learning to thrive inside it.