I’m generally an upbeat person, not given to bouts of sadness or melancholy, and, luckily, I’ve never suffered from serious depression. Bad weather doesn’t drag me down. In fact, I like the rain – I better, I live in Seattle. But this year, the winter months seem to last longer than usual, and slowly but surely even I begin to yearn for a change of season.

I’m not alone in this regard. Many of my clients tell me how much harder they find it to get out of bed when it’s still dark outside on their way to work and dark again when they get home.

“I just don’t have the energy, not even for the things I normally like to do,” one of them told me. “Everything seems to depress me.”

While it is perfectly normal to feel down from time to time, mood swings, even if they don’t persist for too long, should not be ignored. Seasonal affective disorder (SAD), sometimes more casually called the “winter blues,” can seriously affect how a person is able to function and carry symptoms not unlike depression. The point is not to underestimate SAD, which can get worse over time, potentially resulting in difficulty with concentration, anxiety, social withdrawal, alcohol and substance abuse, even suicidal thoughts and behavior.

“SAD is a mood disorder, and although it is generally thought of as a winter problem, it can also occur in other seasons,” says Jonathan Alpert, a Manhattan-based psychotherapist and life coach. “The major distinction between SAD and other forms of depression is that it occurs at the same time every year, for at least two years, and there’s a remission of symptoms off-season.”

One of the causes, he says, is lacking sun exposure for people who live in the northern hemisphere. Shortage of vitamin D may play a role but also low serotonin levels, a brain chemical that affects our moods, as well as an unbalance of melatonin, a hormone responsible for our sleep patterns. It may also be that our inner biological clock, known as the circadian rhythm (the thing that gets out of whack when you are jet-lagged), is disrupted when days are shorter and nights are longer.

So, how worried should you be about SAD? First off, you want to make sure you are not experiencing the symptoms of something more serious. If you have suffered from emotional disorders or depression in the past, or if there is a family history concerning depression, you should definitely tell your doctor about it. But before you ask for anti-depression medicines, you may want to consider some alternative remedies. Perhaps you will respond to light therapy, a procedure where your body gets exposed to artificial light that simulates sunshine. Or you may take a larger amount of vitamin D supplements, or try St. John’s wort, an herb traditionally used to treat depression, although not without side effects.

In any case, spending as much time outdoors, exercising regularly, and eating a healthful diet can make a significant difference. You may also benefit from Yoga, acupuncture, meditation, and massage therapy.

Stress management and practicing sound sleep hygiene are especially important during such times. So be extra kind to yourself, and when you regain your strength and optimistic outlook, remember what helped you through the doldrums and return to your practices as needed. It can only get easier that way.

Timi Gustafson R.D. is a registered dietitian, newspaper columnist, blogger and author of the book “The Healthy Diner – How to Eat Right and Still Have Fun”®, which is available on her blog and at amazon.com.  For more articles on nutrition, health and lifestyle, visit her blog, “Food and Health with Timi Gustafson R.D.” (www.timigustafson.com).