What is Seasonal Affective Disorder?

For most of us, the sadness that comes with watching the days begin to shorten and the temperatures start to drop, as summer gives way to fall, is tempered with anticipation for the holiday season trifecta; Halloween, Thanksgiving, and Christmas. For some, however, this time of year kicks off seasonal affective disorder (SAD), which is a type of depression that comes and goes with the seasons. Symptoms of SAD typically start in the late fall and continue through the winter months, draining energy levels and bringing feelings of moodiness and depression.

SAD tends to be more commonly found in women and young people, with incidence increasing the farther away from the equator. While the exact cause of seasonal affective disorder is, currently, unknown, the change in the amount of sunlight may disrupt the body’s internal clock, leading to feelings of depression. Research also indicates that an imbalance of the brain chemical, serotonin, may play a role, as may the body producing too much melatonin, a sleep-regulating hormone, and too little vitamin D.

Seasonal affective disorder is not something to take lightly, and it is not considered a separate disorder with depression-like symptoms: it is a full-fledged type of depression. In order to be officially diagnosed with SAD, the full criteria for major depression must be present and coinciding with specific seasons for at least two years. Seasonal periods of depression must occur more often than periods of depression that are not associated with particular seasons.

Symptoms of Seasonal Affective Disorder

Symptoms of SAD commonly appear in the fall and go away when the days get longer and there is more sunlight in the spring and summer. For a much smaller group, the opposite is true and symptoms begin in spring or summer. For almost everyone, though, symptoms that typically start out mild and become more severe as the season progresses include:

  • Feeling depressed most of the time
  • Losing interest in favorite activities
  • Low energy levels
  • Difficulty falling and staying sleeping
  • Changes in appetite or weight
  • Sluggishness or feeling agitated for no identifiable reason
  • Difficulty concentrating and loss of focus
  • Feeling hopeless, worthless or guilty
  • Suicidal ideation and frequent thoughts of death

Fall and winter SAD

Symptoms specific to the typical winter-onset SAD often include:

  • Oversleeping and difficulty waking up
  • Appetite changes, especially a craving for foods high in carbohydrates, often leading to weight gain
  • Low energy and feeling tired all the time

Spring and summer SAD

Symptoms specific to the less common summer-onset SAD may include:

  • Insomnia
  • Poor appetite, often resulting in weight loss
  • Agitation or anxiety

In the U.S., approximately 20 percent of the population is affected by SAD, with 6 percent suffering from the most severe levels of depression. The main forms of treatment are light therapy, psychotherapy and medications, which may be combined and supplemented with stress management and exercise programs. While SAD can be debilitating for those severely affected, the good news is that 60 to 80 percent of SAD sufferers experience marked benefits from light therapy, alone.