Did you know that nearly 10 percent of Canadians ages 12+ are affected by a mood disorder (1)? A mood disorder refers to a general emotional state or mood that interferes with one’s ability to function – major depression disorder (MDD), anxiety and bipolar disorder (BP) are all commonly recognized mood disorders. However, did you know that seasonal affective disorder, a form of depression, is also a mood disorder?

While mood fluctuations brought on by the change of seasons have long been a part of human nature, (we all get the “winter blues” every once in a while), the more formal term, seasonal affective disorder (SAD), was coined in 1984 by researchers at the National Institute of Health. The researchers noted a seasonal pattern of depression within themselves, which they linked to reduced sunlight during the winter months.

Although it seems almost normal to feel a little down when those long, darker days of winter set upon us, it’s important to understand that SAD is a subtype of major depression or bipolar disorder. In fact, the hallmark features of SAD include recurring episodes of major depression, mania or hypomania that appear on a seasonal basis and then remit (2). Diagnosis can be confirmed once there is a seasonal pattern of onset and remission.

And although we often think of SAD as a winter affliction, “seasonal” onset can also include the spring and summer seasons (3). Known as “summer depression”, symptoms can include insomnia, reduced appetite and weight loss whereas a typical fall-winter SAD will see opposite symptoms such as increased sleep, carbohydrate cravings and weight gain. The ties that bind both forms of SAD are part of the diagnostic criteria for major depressive disorder that include but are not limited to depressed mood and diminished sense of pleasure for most of the day on an ongoing basis, fatigue or loss of energy, a diminished ability to think or concentrate and feelings of worthlessness.