A big misconception about SAD is that it’s just something in your head, however it’s in fact a diagnosable subset of major depression. To be diagnosed with SAD, symptoms must reoccur at least twice at the same time each year, and then subside for the rest of the year.
Although SAD is typically considered a fall and winter disorder, in a small number of cases, symptoms may be triggered by the longer, brighter days of summer. Some people also experience symptoms during periods of overcast weather, regardless of the season.
According to the American Psychiatric Association, about 5 percent of adults in the United States experience SAD. For many, this is a recurring condition that visits from late fall to spring, with the most difficult months being January and February. Both children and adults can get SAD. However, it usually develops between the ages of 18-30.
For centuries, scientists and observers of human nature have noted that winter’s shorter days and longer nights have a psychological effect on people, particularly those living in northern climates. But this phenomenon wasn’t officially acknowledged until the 1980s, when psychiatrist Dr. Norman Rosenthal fully described SAD and pioneered the use of light in its treatment.
Our bodies shift their circadian rhythm, or 24-hour biological clock, to match the seasons. However, since our daily schedules remain fixed, our lives fall out of sync with our biological clocks during the winter months. As a result, many people start exhibiting symptoms of SAD.
- Sleep disturbances
- Change in appetite
- Feeling inadequate
- Weight gain
- Inability to concentrate
- Loss of interest in things once enjoyed
- Thoughts of suicide
A contributing factor to SAD is a lack of sunlight
In recent years, scientists have linked SAD to melatonin — a hormone produced by the tiny pineal gland at the base of the brain. The amount of melatonin released into our blood stream is regulated by the amount of light that passes through the eyes — the less light, the more melatonin.
When darkness falls, melatonin lowers our body temperature and makes us start to feel sleepy. Similarly, when the days shorten in winter, less light is available, and melatonin is released into the system for longer stretches of time.
People experiencing milder “winter blues” can often chase away their symptoms by taking in more natural light. However, more severe cases of SAD often require daily phototherapy. Most studies have shown that about 75% of individuals experiencing SAD show improvement when using light therapy.