What is seasonal affective disorder?

Seasonal affective disorder (SAD) is a type of depression that only seems to strike people during the winter months. It’s more common among people living at higher altitudes. SAD is a rather hotly debated topic among academic circles. Few doctors are familiar with the condition, and many in the psychiatric community are not convinced it’s a legitimate illness. Nevertheless, seasonal affective disorder is listed in the Diagnostic and Statistical Manual of Mental Health Disorders 9DSM), published by the American Psychiatric Association, and research on the topic is ongoing.

Who gets seasonal affective disorder, and how common is it?

The prevalence of SAD varies by location. Whereas it’s estimated that only 1% of Florida residents have SAD, it’s believed to affect around 5% of U.S. adults overall. (Cassinos-Carr, 2012) The condition is rare in countries within 30 degrees of the equator, suggesting a strong link to climate conditions. (Fieve, 2006) Three out of four SAD sufferers are women, according to Mental Health America. It usually starts in adulthood, with an average age of onset around 23.

What causes seasonal affective disorder?
Scientists still aren’t entirely sure what causes seasonal affective disorder, though there are several theories. Many who study this condition believe it is related to sunlight and how seasonal changes in light/dark cycles impact our circadian rhythm, or the body’s internal clock. This can in turn affect sleep patterns (disruptions in sleep have long been linked to depression), as well as the release of serotonin, a brain chemical that affects mood.

Another leading suspect is behavior. “People might tend to stay indoors more when skies are gray,” says Robert Ruxin, M.D., chief of outpatient psychiatry for Kaiser Permanente’s South Sacramento Medical Center. “So if people are hibernating because they don’t like to be out in gray’ weather, that might be one of the reasons they feel depressed, because exercise is an antidote to depression.” (ibid, p. 81) It’s also possible there could be a genetic component.

Signs, symptoms & diagnosis of seasonal affective disorder
In order for a diagnosis of SAD to be made, one must experience 3 consecutive winters with depressive symptoms, followed by a complete remission during springtime and summer. Such depressive symptoms can include things like mood changes, anxiety, sleep disturbances, lethargy, overeating, weight gain, irritability, or a loss of libido. Here is the official criteria for seasonal affective disorder:

A) A “regular temporal relationship” between a particular time of year and the onset of depression, except in cases where there are environmental stressors that could explain it, such as seasonal unemployment.

B) The depression remits at a particular time of the year.

C) A consistent pattern of this seasonal depression over the last 2 years.

D) The seasonal major depressive episodes must “substantially outnumber the non-seasonal major depressive episodes that may have occurred over the individual’s lifetime.” 9DSM-IV)

Treatment for seasonal affective disorder
Aside from the typical regimen of antidepressants (which I do not recommend), the most common treatment for SAD is light therapy. Light therapy (in which a person sits for a period of time each day under special lamps meant to mimic natural sunlight) is believed to alter a person’s physiology in a way that improves their depression. A number of studies have found beneficial effects in light therapy.

The amino acid tryptophan has been shown to have a positive effect in some studies. It works as a building block for brain serotonin. Though not available as a supplement, it can be obtained in your diet: foods like turkey, cheese, eggs, nuts, beans, and milk are all high in tryptophan. (Fieve, 2006)

Lifestyle interventions can also be extremely helpful. Since this disorder may be partly related to the inactive lifestyles people in colder climates often revert to in the winter, just getting out more often and making sure you are getting regular exercise can lead to a substantial improvement.