Vol. 1, Ep. 5 "Humbugs" (2007)
What is Seasonal Affective Disorder (SAD)? (Episode 5)
Seasonal depression, often called seasonal affective disorder (SAD), is a depression that occurs each year at the same time, usually starting in fall or winter and ending in spring or early summer. It is also known as "the winter blues" or "winter depression" because people who suffer from SAD have many of the common signs of depression.
Symptoms of winter SAD include:
- Sadness & anxiety
- Increased need for sleep
- Decreased levels of energy
- Weight gain
- Increase in appetite
- Difficulty concentrating
- Increased desire to be alone
- Interpersonal difficulties (especially feelings of rejection)
- A heavy leaden feeling in the arms and legs
- Acute hatred of Chrismas and holiday traditions
Between 4 and 6 percent of the U.S. population suffers from SAD, while 10 to 20 percent may suffer from a more mild form of winter blues. Three-quarters of the sufferers are women, most of whom are in their 20s, 30s, and 40s. Though SAD is most common during these ages, it can also occur in children and adolescents. Older adults are less likely to experience SAD. The illness is more commonly seen in people who live at high latitudes (geographic locations farther north or south of the equator), where seasonal changes are more extreme. It is estimated that 1 percent of Florida residents, 4 percent of Washington, D.C. residents, and nearly 10 percent of Alaska residents suffer from SAD.
The exact cause of this condition is not known, but the influence of latitude on SAD strongly suggests that it is caused by changes in the availability of sunlight. One theory is that with decreased exposure to sunlight, the biological clock that regulates mood, sleep, and hormones is delayed, running more slowly in winter. Exposure to light may reset the biological clock. Another theory is that brain chemicals that transmit information between nerves, called neurotransmitters (for example, serotonin), may be altered in individuals with SAD. It is believed that exposure to light can correct these imbalances.