The dark and extremely gloomy days of Seattle are now settling in. For runners in this region who work normal day shifts, this signals the dark days of running that last up to five to six months, depending on what time of day one runs and how much free time one has. I find it more gloomy than Anchorage, where I lived and ran six years. I never minded running in the dark there, because the snow and clouds created very powerful ambient light that made running at night very pleasurable. But here, it is dark as a coal mine, and damp. People’s vitamin D levels are unhealthily low, and there seems to be widespread manifestations of seasonal affective disorder (SAD).

First, let’s talk about why this is such a depressing time of year and can be such a bummer place to be.

The absence of natural sunlight impacts the body’s production of two key hormones that impact the body’s sleep-wake cycles, energy, and mood: melatonin and serotonin. Research indicates that melatonin is generated in greater quantities because of longer periods of darkness. Increasing the production of melatonin leads to sleepiness and lethargy. Serotonin, whose production rises with more exposure to sunlight, falls during these shorter days. Low amounts of serotonin are also associated with depression.

Another byproduct of the darkness is a decrease in the production of vitamin D, naturally created by the body. Though researchers have not fully determined whether low vitamin D contributes to symptoms of depression or whether depression itself contributes to lower vitamin D levels, higher levels of Vitamin D are associated with decreased risks of depression. But alas, anyone living in  Canada, and the northern tier of the Lower 48 here in North America all require vitamin D supplements too to make up for the absence of sunlight come fall. Vitamin D also is critical in many key functions: enhancing the absorption of minerals in the gastrointestinal tract and kidney and thus into the blood, and it may protect against tuberculosis, gum inflammation, MS, and some cancers—at least according to my handy nutrition textbook: Understanding Normal and Clinical Nutrition. (I really love this tome – nicely written, well illustrated.) My response is to take vitamin supplements, but that is not enough.

So here I am in dark and rainy Seattle, deprived of naturally produced vitamin D, at higher risk of SAD. This is exacerbated by Seattle’s culture that seems to promote the absence of smiles and eye contact with strangers. What is a person to do?

Easy, go running. While hitting my local running grounds (Greenlake), I heard some walkers recently comment, “This is when the real runners come out.” The observation was referring to the near absence of mobs of fair-weather walkers and runners whose numbers thin by nearly 80% the moment the rains fall and that stygian Seattle glooms settles around mid-October. Paradoxically, running is the perfect antidote to anything resembling SAD or depression or everyday stress. I have done this since I was 15, and I continue running rain or shine, but particularly when it rains.

One of the earliest blockbuster books on the health benefits of running, the Joy of Running, by Dr. Thaddeus Kostrubala, came out way back in1976. In it, Kostrubala was among the first of the self-improvement health gurus to promote using an aerobic activity, running, to help treat mental illnesses such as depression. More recently, in September 2011, the UK-based Telegraph published a typical story that is the grist for many running magazines, Running outdoors can improve mental health. The story touted how running outdoors “can both raise your spirits and give you a real buzz.” Of course there are all sorts of web sites that list evidence-based findings that point to the health benefits of running–stress relief, blood circulation to the brain, chemical releases, sharpened cognitive functions, getting outdoors, and more.

There are also numerous, peer-reviewed scientific papers that highlight the mental health benefits of running, particularly in response to depression. I stumbled on one such paper doing a quick keyword search on the database PubMed, by D.I. Galper, et al., in the January 2006 edition of the journal Medicine and Science in Sports and Exercise, called “Inverse association between physical inactivity and mental health in men and women.” That study looked at the associations between measures of physical activity and mental health in a large group of more than 5,400 men and women. Galper and his colleagues found that cardio-respiratory fitness and habitual physical activity were associated with lower depressive symptoms and greater emotional well-being.

Of course I and other dark and rainy weather runners did not need this study to confirm what our bodies are telling us every time we get out of our homes and get wet while splashing outdoors. I realize that not everyone has the time to get out after busy days. They may have classes, second jobs, kids, or all of the above. But even in the rain, in the blackness of a fall day, a run or even a walk is sure to improve one’s mental outlook, boost one’s mood, and stimulate the body’s chemistry. Here’s to the days and months ahead of soggy shoes, headlamps, and hopefully a few hellos from water-logged runners. You’re a fine crew.