Why Cold Exposure Makes Sense in Northern Winters (Even If It Sounds Crazy) (Part 1/2)
If you live somewhere that gets dark by 4 p.m. and feels more like a freezer than a cozy winter postcard, you might think the last thing your body needs is more cold. But here’s the twist—your body may actually thrive on it.
Cold exposure might sound like the ultimate test of willpower, but it’s more than an internet challenge or a biohacker trend. It's one of nature’s oldest, most effective ways to tune our bodies when light is scarce. And if you’re someone who feels off in the winter—tired, moody, or inflamed—your mitochondria might be calling out for this ancient reset.
Let’s unpack what that really means in plain English.
Why Winter Wears Us Down
When we don’t get enough sunlight—especially UV and infrared light—our biology takes a hit. We’re light-powered beings. Sunlight regulates our hormones, fuels our mitochondria, and even helps produce key molecules like dopamine and melatonin that affect mood, energy, sleep, and immunity.
In the summer, we get a natural boost from all that solar input. But in winter? Not so much. And in northern regions, where winter days are short and sun exposure is limited, our biology has to pivot to another source of support.
That’s where cold comes in.
Cold: Nature’s Backup Plan for Sunlight
From what I’ve been learning (and playing around with in my own life), cold isn’t just a stressor. It's a biological signal—an activator of some of the same pathways that sunlight turns on in the body. In fact, cold can mimic or even enhance some of the light-driven processes our bodies rely on to stay healthy.
When you expose your skin to cold, several powerful things happen:
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You generate more melanin and other POMC byproducts – These molecules help protect and repair your body at a cellular level, just like they do with sun exposure.
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You shift white fat to brown fat – Brown fat is your body’s “thermal battery.” It burns calories to keep you warm—supporting better glucose control, energy, and even reduced inflammation.
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Your mitochondria get stronger – Cold exposure increases mitochondrial density and function. That means better energy, better hormone signaling, and better recovery.
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You make your own internal light – Cold helps your body emit and recycle light internally. Think of it as building your own solar battery from the inside out.
Cold Is More Than a Hormetic Stressor
A lot of modern advice around cold therapy frames it as a “hormetic” stressor—something uncomfortable that ultimately makes you stronger. But what I’m starting to understand is that cold is more than just an adaptation tool. It’s a signal your body can use to reorient when solar input is low. Kind of like a backup generator.
Why This Matters in the North
If you live above the 37th parallel (most of the U.S., Canada, and much of Europe), winter light is weaker and more limited. That means:
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Less UV light to activate Vitamin D, melanin, and POMC pathways
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Less infrared light to charge your mitochondrial water and improve energy flow
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Less signal to the circadian system, leading to disrupted sleep, mood, and metabolism
Cold steps in as an alternative signal. It increases endogenous light production, boosts mitochondrial health, and keeps your circadian and metabolic systems from slipping into chaos.
It’s not just about surviving the dark—it’s about thriving in it. Cold exposure is one way I’m playing with that idea this season.
What I'm Noticing So Far
We’re not saying you need to hop into an ice bath tomorrow or roll around in the snow like a polar bear. Personally, I’m experimenting with small, regular doses of cold exposure. And I’m noticing that even a little bit goes a long way.
This isn’t about suffering. It’s about signaling. That feeling of “I want to run inside and turn up the heat” is exactly what nudges the body into a new gear. It feels like a soft reboot, in a good way.
Key Takeaways
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Winter light deficiency affects everything from your mood to your metabolism.
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Cold exposure isn’t just toughing it out—it’s a biologically intelligent way to spark energy production, fat burning, and repair systems.
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Northern dwellers are uniquely wired to benefit from cold, especially when sunlight is lacking.
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Your body is capable of using cold to create light, generate heat, and strengthen your energy systems from the inside out.
So if you’re curious, try easing into it with me. A little cold might be exactly what your ancient biology is craving.
Disclaimer: This blog is based on personal experiences and is intended for informational purposes only. It is not medical advice. Please consult with a healthcare provider before starting any new health practices, especially if you have existing medical conditions.
Want to read part 2? Click here
References:
Quantum Engineering #34 - Outing a Longevity Expert (Dr. Jack Kruse's Patreon)
Additional Dr. Kruse blogs on cold: https://jackkruse.com/?s=cold