Read by Matilda Longbottom

It’s December, the month that features Christmas, Kwanzaa, Hanukkah, and Pearl Harbor Day, as well as such lesser under-appreciated holidays as National Sock Day, National Llama Day, World Pear Day, and (on December 27th) the International Day of Epidemic Preparedness. It’s also the month of the Winter solstice, the longest night of the year, which this year falls on Saturday, December 21st, at 4:19 AM (Eastern Standard Time).

Just how long the longest night is depends on your location. If you’re in Tucson, Arizona, you’re looking at a 14-hour night; in Fairbanks, Alaska, you’re in for a 20-hour night; and if you’re pottering around in a workshop at the North Pole, you’re getting 24 straight hours of darkness with not so much as a sliver of daylight.

December is also the month when many families traditionally read “The Night Before Christmas” – originally published (anonymously) as “A Visit from Saint Nicholas” in 1823. The author, Clement Clarke Moore, only owned up to it 14 years later, explaining that he’d been inspired while on a snowy shopping trip – he was out to buy a turkey – in a sleigh.

He based jolly old Saint Nick on his Dutch gardener. And he flat-out invented the eight tiny reindeer and their names, which has bedeviled us ever since; when seasonally asked to come up with those blasted reindeer names, most of us can only remember six. (Don’t struggle: it’s Dasher, Dancer, Prancer, Vixen, Comet, Cupid, Donner, and Blitzen.) Today some claim that Moore’s “Night Before Christmas” may be the most famous poem ever written by an American, though admittedly he has some competition from Emily Dickinson, Robert Frost, Walt Whitman, T.S. Eliot, and Henry Wadsworth Longfellow.

But let’s set the scene: when the poem opens, everybody in the house is asleep. The mice are conked out. The kids are dreaming of sugarplums. The parents, bundled in nightcaps – after all, it’s 1823, the tail end of the Little Ice Age – have just settled down for a long Winter’s nap. Until they’re abruptly yanked out of bed by all that reindeer commotion on the lawn outside. They behave surprisingly well about this, considering; I know how I act when rousted out of sleep in the middle of the night by raccoons in the garbage cans.

Winter’s naps are important.

Many animals simply sleep the Winter out, among them bears, bats, bumblebees, box turtles, and groundhogs – which supposedly pop out of their cozy burrows on February 2 for a quick look around, though I have to say that no Vermont groundhog would be idiotic enough to do any such thing. (Neither, to be fair, does Pennsylvania’s Punxsutawney Phil; to get him up and shadow-spotting on Groundhog Day, somebody has to shake him.)

Perennial plants spend Winter in a state of stupefied denial known scientifically as dormancy – from the Latin dormire, to sleep. During dormancy, metabolism slows to a barely detectable putter, protecting plants from loss of water and nutrients and from damage due to freezing. Plants know that it’s time to drop off when nights grow longer and temperatures colder.

Key players here are a family of proteins called phytochromes that flop back and forth between two different forms: Pr that absorbs red light, of which there’s a lot in sunshine; and Pfr that absorbs far-red light, of which there’s more in the dark. Essentially phytochrome is a biological on-off switch. Pr (off) absorbs red light from sunlight and turns into Pfr (on), which in turn activates the systems that make plants grow. In the dark, Pfr (on) absorbs far-red light and turns back into Pr (off). You see the wonders of chemistry.

As days become shorter and nights longer, increasing doses of far-red light generate more and more dud-like Pr – to which plants respond with a battery of shutdown responses, including dropping all their leaves. All those gorgeous Fall tree colors, followed by all those heaps of dead leaves on the ground: that’s Pr at work.

Actually – nothing is simple – it’s a little more complicated than that. It turns out that there are at least two different kinds of dormancy. Endodormancy – brought on by long cold Winter nights – clicks in first. This is the result of internal biological changes that keep plants down and out until a certain number of chill hours have passed signaling the end of Winter.

Chill hours are less chilly than they sound; these are above-freezing periods of temperatures between 32 and 45 degrees. Most fruit and nut trees, for example, need somewhere between 500 and 1200 chill hours before they can shake themselves out of endodormancy and prepare for flowers and fruit. (The chill-hour requirement, if all goes well, keeps plants from sprouting prematurely in the event of an unprecedented Winter thaw.) Once a plant has put in its chill hours, it transitions from endodormancy to ecodormancy – think deep sleep to light snooze – at which point the biochemical brakes are off and it just needs some springlike warm temperatures and a decent dose of daylight to wake up.

The world outside our windows right now – all those leafless trees and invisible rhubarb and asparagus plants – that’s endodormancy. Our plants are out.

And they’re not alone. Recent research shows that people, too, deal with Winter by falling asleep. According to the National Sleep Foundation, adults sleep 1.75 to 2.5 hours more during the Winter – most likely due to short days, early sunsets, and cold. Shortened seasonal light levels, scientists guess, may scramble our biological clocks, perhaps promoting an earlier rise in melatonin, a natural hormone associated with sleep – or may reduce our synthesis of vitamin D, which also makes us sleepy, since we’re not getting much in the way of sun.

Not only that, but the quality of our sleep changes. According to a study in the journal Frontiers in Neuroscience, people spend half an hour more in REM (rapid eye movement) sleep in Winter than in Summer – that is, the period of sleep when we’re most likely to dream.

This isn’t a bad thing. I mean, it’s dark, it’s cold, the weather outside is frightful, and the roads are probably awful.

You might as well curl up and take a nap.

After all, that’s what the plants are doing. ❖