The Science of the Winter Blues

We like to think of Hallowe’en as the scariest time of the year, but I personally find the month of November to be much worse. After we turn back the clocks (signaling the end of Daylight Savings), the days get much shorter and colder. As the temperature drops, so will many our moods and energy levels. This seasonal melancholy is often called the “winter blues” – or Seasonal Affective Disorder (cleverly shortened to “SAD”) and if you find yourself maybe a little less motivated or have difficulty getting up in the morning, you could have a case of it.

I met with Dr. Robert Levitan, a research scientist at the Mood & Anxiety Disorder Program at the Centre of Addiction & Mental Health (CAMH) to find out what causes this rather insidious kind of depression. According to Dr. Levitan, “seasonal depression is defined by its timing; it tends to start in the fall, when we change the clocks back, you’ll feel much worse, you’ll feel tired, sluggish, and you won’t be able to think as clearly.”

How common is Seasonal Affective Disorder? Robert says “as many as 15-20% of Canadians probably have some form of seasonal depression,” but about 2-4% more will experience the most severe clinical form. And those figures don’t include an additional third of us that can expect to suffer through “the winter blues” each year.

“as many as 15-20% of Canadians probably have some form of seasonal depression.”

Dr. Robert Levitan, CAMH Toronto

This is an insidious kind of depression that is actually quite different from general depression, at least in terms of the symptoms. With regular depression, “most people will tend to lose weight, lose appetite, not be able to sleep as well. But in seasonal depression, it’s quite the opposite. Patients will crave carbohydrates and fats, they’ll often gain a lot of weight and they’ll tend to sleep a lot more.” It seem like a sort of human hibernation, where we’re instinctively drawn to conserve energy, which makes sense from an evolutionary perspective. Back during the Ice Age, when we didn’t have electric furnaces, heated leather seats and hot-tubs to help us survive the winter, it would be especially beneficial for us to stay inside, sheltered and stockpile our food energy.

The underlying trigger of seasonal depression seems to have to do with light availability. “If you think about it, light and dark cycles have been around since the beginning of time. All of biology organizes around light and dark cycles.”

These internal body cycles are called circadian rhythms and they govern much of our basic biology.

“We take it for granted, but our basic ability to function and our whole sleep/wake cycle is of course driven by light.”

This is over-simplifying a bit, but light helps catalyze the production of serotonin, a neurotransmitter that regulates our mood, keeps us alert during the day. In the absence of light, we produce the hormone melatonin, which helps us go to sleep.

Robert refers to Seasonal depression, as a vestigial process, one that likely helped us in our evolutionary history, but today is more of a nuisance. Luckily there’s a few things we can do to arm ourselves in the fight again seasonal depression and one of them is called “light therapy.” The process involves turning on a brightly powered light in the morning.

“It’s sort of like a car on a cold day, it takes a while to get the engine going and humans are very similar in many ways.”

The experts say it is exposure to the sun at sunrise that’s a key factor in synchronizing our internal body cycles. So in absence of that sun, we can cheat it. The light “fools your brain into thinking it’s a spring or summer morning.”

A typical treatment would be about 30-minutes in the morning, preferably starting before 8am. The light should be bright, about 5000 lux hours, or what you’d get from the sun at sunrise. This light needs to go through your eyes for it to work, so it should be UV-filtered – which is yet another reason to say no to tanning beds!

For more info on Seasonal Affective Disorder check out this infographic or visit this link.

Comic illustration by Joey Matthews. Infographic designed by Richard Nalli-Petta.