It creeps up on you in the mornings.
First, it’s the cold.
Then the dark.
And finally, the snow.
Winter is here.
For many of us, winter represents a slowing down of things. The days are shorter, suddenly you’re less inclined to go to the gym after work. Vacations have settled for the most part, and energies are redirected towards class or work or whatever it is you do.
It can also kind of suck.
Why is it that our moods are affected by this change of season? What is it about humans that makes us so sensitive to these changes? Does this have an evolutionary benefit? What if we get too sad?
To think about why the human mood (in general) changes during the season, we must first think about what mood is. Where did mood come from? One of the earliest forms of “mood,” is hunger. When in a hungry mood, even the most primitive animals will change their behaviour, and begin food-seeking behaviours. Their cytoplasmic cilia might undulate towards a chemical stimulus. They may swim to a shallower depth towards the scent of a school of fish. If you are a hunter, and encounter a bear in the woods, hope that it’s not hungry. It may not eat you. If it’s looking for a meal? Good luck! The point is the moods, in animals, represent a set of behaviours suited to a particular circumstance.
Does this apply to humans? Of course. We gorge the cupboards when we’re hungry. On a macro level, countries and nations suffering from famine and starvation have orders-of-magnitude more unrest and civil war than their well-fed counterparts.
While hunger is a relatively easy “mood” to understand the benefits of, the behaviours and utility provided by more traditional moods like happiness, sadness, and anger, are more subtle, yet equally significant.
Anger can be considered synonymous with threat. People who are angry often feel threatened, and many of the behaviours associated with anger are involved with defense and mitigating a threat. Yelling, like the growling bear, is making yourself “big,” to intimidate an enemy. Elevated heart rate (tachycardia) occurs when you’re angry, in case the most extreme manifestation of anger, violence, is necessary. Sadness can be a little less clear. After all, what could be the evolutionary benefit of something often so painful?
Sadness is afforded power by virtue of the pain it causes. If we are sad about something, our brains want us to avoid that same circumstance from happening again. Losing a job, a messy break up, losing a loved one, these are all circumstances that our brain is telling us we should avoid again, and our behaviours begin to modify in hopes to avoid triggering the sadness again. If you’ve lost your job because you continually showed up late to work, the sadness afforded by the job loss may motivate you to be on time for the train more often in the future. While wallowing over a messy break up, you may find yourself reflecting on the relationship in search of “what went wrong,” and using this information to improve your relationships in the future.
The pain caused by the loss of a loved one is a little more nuanced. What change could sadness drive? There are a few answers. Historically, most deaths were preventable, and the result of a sabretooth tiger attack, or tribal warfare. Sorrow caused by deaths in these circumstances were clearly cause people to be more weary of protecting against tigers, and may either question the benefit of their war or double down and fight even harder. Today, many deaths have a component of lifestyle contributions, and grief after a loved ones death from lung cancer, who smoked, may cause us to question our own habits. The point is, even grief, sadness, and sorrow drive change, and have clear utility on an evolutionary, population level.
So what happens when you get too much of this? Well, depression, for one. A disruption of the normal mood cycle, by any number of factors, can contribute to the development of depression. In the case of anger and happiness, they can contribute to the development of mania. And the fact is, all of us are vulnerable to alterations in our moods when the environment changes, even if it doesn’t represent a frank depressive or manic episode. One of these factors is the season, as we discussed above. For most of us, it’s just the way things are. For some of us, it’s the winter blues. In extreme cases, it’s seasonal affective disorder (SAD).
What is SAD? How is it caused? What about the seasons impacts our moods? Can we use this information to inform SAD treatment? Tune in to part 2 to see!
Dr. Travis Barron is a resident physician in Toronto, Ontario.