Winter “Dormancy” for Humans


The dark days of late fall and early winter have an undeniable impact on our moods and energy levels. Just like plants, the decline of daylight makes many of us want to cease to grow for a while. This desire for dormancy isn’t just some Pinterest-induced yearning for hygge comforts triggered by overwork and overwhelm. It’s part of our basic biology.

Slower metabolisms are often blamed for the winter blues. In fact, it’s more complicated than that. Humans don’t hibernate in the cold like bears do. That means, in some ways our metabolism has to speed up — such as to keep us warm. But our bodies also slow down on certain services to compensate. Those seasonal cut backs can leave us less energetic than at other times of the year.

Let’s look at a few of the seasonal changes that may have you feeling more like curling up with a good book than racing through your homestead project list!

Vitamin D

Deciduous plants drop their leaves in fall and keep them off through winter to reduce energy used for intensive processes like photosynthesis. With declining day light hours and soil life slowing down as the temperature drops, this is a good survival strategy for plants in cold climates.

Likewise, our bodies make vitamin D in a process similar to photosynthesis. We gather UVB rays from the sun to combine with other organic materials from food and our microbiome. Together, these things are reconfigured into a form of Vitamin D that can be used by various systems within our body.

The amount of direct sunlight available for vitamin D production is limited by the available daylight hours in your location and other factors like air pollution. At certain times, like in winter when UVB rays are reduced due to the indirect angle of the sun, our bodies will automatically save on the amount of energy spent making vitamin D.

Since vitamin D is tied in with the immune system and our ability to fight off illnesses like colds and flus that spread easily in cold weather, this might be perceived as an evolutionary design flaw. However, it only seems that way if you assume humans are supposed to spend winter traveling between crowded places rampantly spreading disease.

From an evolutionary perspective, winter would have been our most socially inactive time of the year. Between cold and inclement weather, travel was rare. In a hunker down situation, we’d naturally need less disease protection in cold weather due to less exposure to outsiders.

Calcium Absorption

Additionally, reduced vitamin D production also naturally leads to a slow down in other energy intensive biological processes. For example, calcium is the main ingredient our bodies use for bone maintenance. However, calcium from food is only absorbed by our digestive system when we have an ample supply of vitamin D.

When vitamin D quantities decline absorption of calcium does too. That, in turn, leads to our bodies doing less bone maintenance during low light months.

Again, if you aren’t out doing lots of heavy duty activity (or going through a growth spurt) that requires extra bone maintenance, this temporary service reduction is not a huge risk to long term health. However, it does help explain why people with osteoporosis, or imperfectly healed bone injuries, tend to feel more aches in their bones in winter.

Incidentally, this mutually dependent relationship is also why commercially packaged, calcium-rich foods (like milk) are often fortified with vitamin D3 to compensate for human deficiencies.

From a natural perspective, similar to trees dropping leaves to reduce their energy needs, tying vitamin D production to daylight is a clever biological trick to reduce multiple energy intensive bodily processes with one elegant solution.

Blood Pressure

Another metabolic change that happens to many of us in cold weather is that our blood pressure increases. At first blush, that may not sound like a reduction in normal bodily services. However, the mechanisms that make this happen are very energy efficient.

In response to cold, our blood vessels shrink causing the same amount of blood to move through our bodies at a faster rate of flow. This is the same basic logic behind hydroelectric power. By passing large amounts of fluid through small openings, you generate maximum power with minimal work.

Of course, this kind of energy production poses serious risks down stream. In most cases, it leads to the collapse of sensitive ecosystems due to the altered flow rates.

In our bodies, long-term constriction of blood vessels to expedite blood flow takes a serious toll on our organs and extremities. That’s why maintaining low blood pressure is a hallmark of good health. Still, for short periods such as to survive freezing conditions, this is a terrifically efficient way to keep the body working using fewer physical resources.

While effective, the downside is that elevated blood pressure, even short-term, can cause fatigue. That makes doing normal activities and being productive at work harder in cold weather.

Again, in evolutionary terms, blood pressure induced fatigue was probably a non-issue because less activity in winter would have been normal. So, if a trip out to grab more firewood tired you out, you’d just rest by the fire to rejuvenate.

Today though, we have all sorts of innovations like electricity, fast-transportation, and (often unreasonable) expectations from employers and social networks that complicate the practical realities of living by our evolutionary biology.

The Evergreens

Of course, there are also some people who have a natural capacity to thrive in short days and colder weather. Like evergreens in the forest understory that do most of their growing after taller trees drop their leaves, these built-for-winter people may have genetic adaptations that make them more suited to tolerate cold or low light conditions. Their diets may also play a role. Additionally, as we learn more about the human microbiome, we’ll likely discover that particular kinds of gut bacteria improve cold hardiness in humans.

Your amount of training for the cold is also a factor. If you were raised with cold winters and spent most of your youth outdoors, then you’ll have better cold conditioning than someone who grew up in a warm climate. Alternatively, if you intentionally train for the cold, such as by doing winter sports or ice water bathing, you can reduce your sensory perception of cold.

Desensitizing your skin to cold, through regular exposure, delays the rate at which your body feels the urgent need to constrict blood vessels or take other fatiguing actions to warm up. Dulled cold receptors can stall the natural tendency to shiver and shrink blood vessels long enough for outdoor activities to warm you up. Then, you never experience the stress and fatigue of blood pressure fluctuations.

Just like people can train their muscles to become stronger, you can train your body to be less reactive to cold temperatures so you can thrive outdoors, even in winter.

Embracing Nature

Thanks to the Epicurean homesteading lifestyle, I get to spend a lot of time every day observing seasonal behaviors and changes in plants, animals, and the ecosystem around me. I’ve noticed that all life forms — from large goats to microscopic soil life — alter their modes of living in response to shorter, colder days.

Soil microlife go dormant or recede deeper underground lowering nutrient availability for shallow-rooted plants. Cold hardy plants slow their above ground growth and root deeper in the earth where temperatures are warmer and nutrients are still bioavailable. Leaves drop. Insects go dormant or semi-dormant in that leaf debris, biding their time until the food flows again in warm weather and increasing daylight.

Many mammals retreat to their shelters in cold. On warm, sunny days they venture out. Their winter diets are dominated by carbon rich dried leaves, sugary dried or cold hardy fruits, desiccated seeds, and new growth stems. Birds and furry creatures also put on new coats, and undercoats, to protect them from the cold.

Countless other minor and major changes happen. But even this short list offers insight into how life forms naturally respond to environmental changes. Observing these details in so many other life forms has helped me recognize the analogous patterns in my biology. Over the years, it’s become obvious how insane it is to try maintain the same lifestyle, energy, or productivity levels year-round.

Advice from a Tree

You may be wondering about all the tree analogies peppered through this post. I could have just as easily written about things like the way chickens reduce their egg production because of their hormonal relationship to light. Similarly I might have focused on how goat milk quantity declines but fat and nutrient content increase in cold weather as a natural mechanism to keep baby goats warm during feedings. Or perhaps I could have focused on how soil bacteria are triggered into action by chain chemical reactions based on soil temperature.

In fact, there are so any natural, observable responses to reductions in light quantity and temperature fluctuations, that I could spend my life writing about this topic and barely scratch the surface. However, for me, my initial meanderings into understanding the biology of seasonal adaptation were tree-inspired.

About 13 years ago, in the gift shop at the US National Arboretum, I came across a note card titled “Advice from a Tree”. I’ve forgotten the exact words. But the gist – embrace the seasons, bend don’t break in the wind, and enjoy simple pleasures — has stuck with me.

The seemingly simple sensibility of those ideas resonated because I read them just as I was reawakening to the natural world. I was trying to connect with nature so I could stop feeling like an animatronic version of a human. Trading productivity for a paycheck, then dutifully spending it to keep the economy growing, had lost its luster. And those ideas pointed the way out of the daily grind.

Subsequently, in the past 8 years of creating and inhabiting a homestead garden paradise, full of all sorts of exotic and native trees, I’ve come to know those ideas were just a hint of what lessons could be learned from nature. They also weren’t entirely accurate.

Only the young supple stems of trees bend. Older more rigid growth of healthy trees can stand its ground as long is it has a solid foundation of deep and diverging roots. Trees that live in the fast lane — sacrificing critical root development for showy top growth — get blown over or heaved out in a bad weather.

Also, it’s not the seasons on the calendar that trees follow, it’s the complex series of environmental changes that occur in relationship with light, temperature, humidity, nutrients in the soil, qualities in the air, and so much more that they truly live by. Trees respond to an intimately connected system of life forms and non-living chemical reactions that communicate through time, space, and each other. It’s like magic.

And of course, there is nothing simple about anything made by nature. Incomprehensibly elaborate ecosystems and millions of years of evolutionary trial and error went into the making of everything that seems “simple” to us today. Most of the improvements we’ve made to plant or animal life relate only to our very narrow desires and sometimes trigger catastrophic impacts (e.g. swine flu, citrus or banana blights, climate change).

Our ability to enjoy simple pleasures is also complicated. We’re wired in ways that make it easier to enjoy dopamine-driven activities that feed our desire for instant gratification. Quite frankly, it’s simpler to escape into an action movie, video game, scratching a lottery ticket, or going shopping spree using credit cards because these activities were strategically designed to illicit dopamine responses and overtake reason. It takes extra effort to get wired back into meaningful communication with nature and enjoy natural pleasures.

In addition to those more nuanced views, I’ve also discovered I totally relate to deciduous trees and their need for chill hours in winter. Chill hours are the times when it is cold enough that trees go into a kind of deep resting mode similar to dormancy. They do the tree equivalent of snuggling under the covers, disconnecting from technologies, and forgetting the world outside for a while.

Every deciduous tree, and some evergreens, have their own exact number of hours of chilling out that they need to be ready to flower and fruit the next year. If they don’t get them, then come spring, they simply don’t flower. This is one of the factors that impacts tree selection and fruit production for home orchards. But it’s also another great lesson we can learn from trees.

Sometimes we really do need to take the time to enjoy deep resting that will ultimately make us more fruitful in the future.

In the spirit of that encounter I had in the gift shop, I’d like to share some of the life-improving concepts that Epicurean homesteading and a deeper connection to nature have taught me about living well. I hope these ideas will reach and resonate with those of you who need them, just like that Advice from a Tree did for me.

To keep the reading light, I’ll be sharing these ideas in a series of posts spread out over the dark days ahead. Please check in as you have time or subscribe to be notified when new posts go up.

How do you feel right now?

In the meantime, I hope this post has given you a sense of how completely natural it is to have fluctuations in your health, energy, and outlook based on your environmental conditions. But, let me warn you, recognition is the easy part. Using that information to create patterns of living that support your health, mental state, and connection to nature requires thoughtfulness and commitment!

If you are up for that, then here’s a simple way to get started right now.

  • Begin with a deep breath.
  • Ask yourself… How do I feel right now?
  • Wait a few moments before you try to formulate an answer.
  • If possible, act on your answer.
    • To alleviate discomfort: Take a nap, a walk, a drink of water, a few minutes to meditate, or do whatever other natural activity available to you that is most likely to alleviate the dominant feeling causing that discomfort.
    • If you feel terrific: Try to pinpoint the specific things — sleep, diet, exercise, relationships, environment, activities, meaningful work, etc. — that may be contributing. Use that information to alleviate future discomfort.
  • Repeat this process as often as you can.

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