Sometimes I manage to strike a chord with the things I write, and that was the case last June. My subject was mental health, and this is how I began:

“The point I’ll try to make is that we must understand mental health better because about 20 percent of us will experience a mental disorder during our lifetime. It’s all around us. And we must deal with that reality better than we do. In our families, in our companies, in our society at large, we cannot continue to sweep it under the rug.”

I didn’t know what to expect in terms of your response, not least because I wrote briefly about my own family’s experience — with their permission — and my youngest daughter’s multiple suicide attempts (she’s doing well now). Was I getting too personal? Did this have any place in a trucking magazine?

I’d written previously that “over-worked, under-paid, and hyper-regulated drivers” might well find themselves with mental health issues, guessing that depression could be “utterly rampant, especially amongst the driving crowd.” I further guessed that “almost nobody knows how to recognize the signs of trouble.”

Well, I was right. And rarely have I had a bigger response to an editorial. I couldn’t possibly publish any of the more serious e-mailed notes I received, because all of them revealed even more about other lives than I had about my own. Very private stuff.

I heard from a trucking mother suffering the anguish of losing a kid by suicide. I had one heart-rending e-mail from a driver who described his symptoms and asked if I thought he needed help. They and many, many others thanked me for raising the general issue of mental health publicly. Everyone urged me to stick with the subject.

I promised I would but the opportunity didn’t arise again until now, prompted by a message from a driver I’ve known for some time. Seems he suffers quite severely from something called Seasonal Affective Disorder, or SAD. He told me about his affliction in some detail and wondered if maybe I should write about it here, thinking it might be common — and commonly misunderstood — in the tough-man world of trucking. So I looked into it.

And as he suggested, I’d bet my next pay cheque that SAD is hardly known at all, though I think it’s universally recognized. If that seems like a contradiction… well, it is. SAD, you see, can start as what we normally dismiss as the simple winter blues.

I get them, you get them, pretty much everyone in Canada does. For most of us, a sunny day that speaks of spring will lift our spirits. Two or three such days in a row and we’re ready to fight again. But it seems not everyone can break out of it quite so easily. For some folks, things are much darker than that.

Of course I went to the Internet to bone up on SAD and found a useful video at the website of a place I know all too well, the Centre for Addiction and Mental Health in Toronto, CAMH for short.

In that video Dr. Robert Levitan, the hospital’s senior scientist and research head in the Mood and Anxiety Disorders Program, explains SAD in its various forms, everything from clinical depression to the simple winter blues. He says that 2-5 percent of Canadians suffer from severe clinical depression that appears as the days get shorter and we slide into winter. Another 10-15 percent show a milder but still serious depression, and a further 25-35 percent of us just have those blues.

I also found cogent explanations at the Mayo Clinic’s website , where I learned that SAD can also start in spring and summer, though more often in fall and winter. Symptoms include: depression, hopelessness, anxiety, loss of energy, a heavy, leaden feeling in the arms or legs, social withdrawal, oversleeping, loss of interest in activities you once enjoyed, appetite changes, weight gain, and difficulty concentrating.

SAD is diagnosed more often in women than in men — by a ratio of four to one — but men are more likely to have severe symptoms. If not treated, SAD can get worse and lead to suicidal thoughts or behavior, work problems, and substance abuse.

If you’re a manager or supervisor, I’d urge you to do a little learning yourself and keep an eye out for these signs, especially amongst your driving staff, who already have a lot on their shoulders. Call it preventive maintenance.