The when is predictable, but researchers can't say how.
Seasonal Affective Disorder or its milder form, the 'winter blues,' is a subcategory of depression related to the change in the amount of daylight common in the winter months.
However, the triggering mechanism is something unique. Every fall and winter the disorder comes back, but as sunny days reappear, the symptoms wear off, said Janis Anderson, a UNM lecturer who has been studying SAD since 1985.
According to the SAD Association's Web site, half a million people are affected with the disorder every month, which is more common in women and 18 to 30-year-olds. But it is not simply a dislike for the cold winter months, Anderson said.
"It is more than a belief or attitude, it is a whole syndrome that includes a lot of physical changes as well as a loss of interests, pleasure in normal activities or sad feelings," she said.
The condition was first identified in the early 1980s. Although researchers cannot pinpoint what triggers SAD, a possible cause is that sufferers are not receiving enough light, increasing the production of melatonin, a hormone that makes people drowsy.
Get content from The Daily Lobo delivered to your inbox
For people to be diagnosed with SAD, they need to have experienced symptoms such as changes in sleep pattern, fatigue, an avoidance of social contact, cravings for carbohydrates and a loss of self-esteem for three or more consecutive winters.
Anderson said melatonin is a possible culprit for the cause of the disorder, but there haven't been any studies to prove it.
"We have hunches and hypotheses, but nothing that has been proven without a doubt," she said.
Paula Clayton, a UNM professor of psychiatry, said one way to look at any illness is to evaluate a person's family history. SAD could be passed along generations because it involves neurotransmitters, particularly those that promote activity in the brain.
Health officials have found a successful way to treat the disorder by simply exposing patients to more light.
"If they are in a situation where they get more light, the depression improves," Anderson said.
Getting an ample amount of light, at least an hour per day, increases the chances of overcoming the disorder by 80 percent. But that light source needs to be safe, and she said it is not as simple as "putting more bulbs in your house."
Patients can carry out normal activities such as reading or writing while sitting in front of a specially designed light box that allows light to enter directly into the eyes. The boxes can emit up to 10,000 lux of light, equivalent to a bright summer day. According to the Web site, the treatment is effective as long as it is done daily.
When light therapy is not available, health officials suggest remaining active during the daylight hours of winter. As with any other form of depression, antidepressants can help.
"Anytime somebody feels like they have a depression, they really ought to talk to a mental health person," Anderson said. "Especially if they feel bad nearly every day for a couple of weeks or more."
