Science

Human hibernation: the restoring effects of hiding away in winter


I sometimes think that winter doesn’t truly start until February. Once the final sunny moments of autumn have gone, I’m bounced along by preparations for the festive season. Even after the final New Year corks have popped, my own reforming zeal gets me through. I may not be tempted by dry Januaries, diets and punishing exercise regimes, but I’m always a sucker for a fresh start, for plans drawn up on new stationery and commitments made to improve myself.

But by early February, I’m sagging. Tired, hungry and sick of the dark, my motivation has run out, my bank account is empty and the world feels soggy underfoot. I start to skip my yoga class and social invitations feel like an imposition. The urge to pull the duvet over my head becomes very strong indeed.

Humans cannot actually hibernate, but in the coldest months of the year, many of us are drawn to something similar. We want to batten down the hatches against the treacherous weather outside, preserve our energies, lay on fat. If only we could suspend the demands of life, just until the sun comes out again, all would be well.

Is it such a bad thing, this desire to hibernate until spring? After all, it feels like a natural response: winter simply demands that we slow down rather than drop out altogether – why can’t we find a way to do this?

I recently visited hibernating dormice at Wildwood Trust just outside Canterbury. Dormice are one of only three UK mammals to hibernate (alongside hedgehogs and bats) and they do so for half of each year, retreating to their nests with the first frosts in October or November, and only emerging when food is abundant again in April or May. In late summer they gorge on fruit, storing the energy as easily accessible liquid fat just beneath the skin. As I learned when I held one – a perfect ball of amber fur rolling in my palm like a marble – you can leave fingerprints in a sleeping dormouse.

To get through this long period without food, a dormouse will slow down its metabolism to the extent that it consumes almost no energy at all, waking briefly every 10 days to keep its organs in working order. We humans, having a few more worldly commitments and physical limitations than your average dormouse, are unable to do the same, but we can allow winter to modify the rhythms of our lives.

Everything about me changes in winter – and I let it happen. Winter is a time to enjoy the pleasures of solitude, to dream and contemplate. It opens up a space in which I can mass my energies, to restore and repair. I want to eat cooked food instead of raw, comforting carbs over fresh flavours. I want to revisit beloved old films and spend time pottering in the company of the radio. Gone are the splashy novels of summer; winter urges me towards thoughtful, ambulatory reading, chewed over in lamplight. In winter, I can spend hours in silent pursuit of a half-understood concept, or a detail of history. Winter has patience. There is nowhere else to be, after all.

While summer often wakes me at 4am with dawn, in winter I can sleep for hours, surrendering to my bed shortly after 9pm, and drowsing there until my morning alarm. Our recent ancestors would have known this pattern well; after all, electric light has only been with us for just over a century. Before that the winter nights were very long indeed.

Sleepy as I am in winter, I find that I rarely slumber right through. Instead, I often wake in the middle of the night and spend an hour or two mulling over my thoughts, sometimes getting up to read, write or meditate, before returning to my bed to sleep until morning. I used to worry over these moments, considering them to be insomnia, but A Roger Ekirch’s book, At Day’s Close: a History of Nighttime, convinced me otherwise. Waking in the midst of a long winter night is, he argues, a form of sleep that would have been entirely normal before light was at our command. Nights were divided into a first and second sleep, with a “watch” in between, during which people would pray, reflect, make love or indulge in quiet conversation with family. It was an intimate time, so private and mundane that it barely merited a mention.

A 1996 study by Thomas Wehr and colleagues suggests that we could fall back into this pattern given the right conditions. Wehr deprived his subjects of artificial light for 14 hours at a time in an attempt to replicate the prehistoric night. After several weeks, the participants fell into a routine of lying awake in bed for two hours before falling asleep for around four hours. They would then wake up and enjoy two or three hours of time that was characterised as contemplative and restful, and then take another four hours of sleep until morning. Most interesting of all, Wehr observed that the midnight watch was far from an anxious time for his subjects. They felt calm and reflective in these moments, and Wehr found that they had elevated levels of prolactin in their blood, a hormone more usually found in nursing mothers. It usually stimulates milk production, but in this context it seems to produce feelings of contentment and calmness. Wehr suggested that the watch was a unique state of consciousness with an “endocrinology all of its own”. Waking during this natural break in sleep seems to release a cocktail of hormones that isn’t found at any other point in our existence.

Is this, then, our human version of hibernation: a thoughtful mode of being that’s profoundly restorative, brought about by the conditions of winter? Perhaps, but I prefer to see hibernation as a useful analogy rather than a biological imperative – after all, winter only comes to populations who live far from the equator; wintering is not a universal human experience.

We also need to understand the healthy limits of our urge to hide away in winter. In regions where solitude is forced upon communities through impenetrable weather, careful preparations are made to ensure that life remains stimulating and joyful during the dark months. Hygge may have been a lifestyle trend in the UK, but closer to the Arctic Circle, those cosy candles and comfort foods are tools of self-preservation. In Nordic countries, it’s common to stock the freezer with cakes and pastries over winter, ready to offer hospitality to anyone who comes to the door.

The sauna is one of the ways that Finnish people battle against the cold. It is a place of refuge and a place that brings a sense of conviviality during periods of isolation. Chosen or not, our periods of hibernation need to be punctuated with moments of social contact, or else we unravel.

I’ve learned to find my own way through winter though. I also seek moments of light and heat to keep my spirits high. In recent years, I’ve developed the (admittedly slightly eccentric) habit of retrieving discarded Christmas trees and squirrelling them in my back garden to light a series of spectacular, resinous bonfires on the darkest nights.

I’ve learned to seek out some of the older winter festivals, too, which mark the beats of the season until the coming of spring. In January I attend one of Kent’s growing number of wassails, a half-pagan, half-Christian ceremony in which an apple tree is fed a tribute of cider to encourage a good harvest later in the year. And I pause on 1 February to mark Imbolc, the Gaelic festival that marks the start of spring, when the ewes are pregnant and the first snowdrops are appearing.

Perhaps we can actually learn more from badgers and frogs than we can from dormice. Instead of hibernating, they fall into states of torpor for short periods of time when food is scarce. It seems to me that this is a model that works for our own winters, conserving our energies by avoiding the worst ravages of the cold rather than dropping out of life altogether.

Wintering: How I Learned to Flourish When Life Became Frozen by Katherine May is published by Rider at £14.99. To buy a copy at £13.19, visit guardianbookshop.com



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