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 more than just
"the winter blues" or "cabin fever." A rare form of SAD
known as "summer depression," begins in late spring or early summer
and ends in fall.
Symptoms
People who suffer from SAD have many of the common signs of depression:
Sadness, anxiety, irritability, loss of interest in their usual activities,
withdrawal from social activities, and inability to concentrate. They often have
symptoms such as extreme fatigue and lack of energy, increased need for sleep,
craving for carbohydrates, and increased appetite and weight gain.
Symptoms of winter SAD include:
- Fatigue
- Increased need for sleep
- Decreased levels of energy
- Weight gain
- Increase in appetite
- Difficulty concentrating
- Increased desire to be alone
Symptoms of summer SAD include:
- Weight loss
- Trouble sleeping
- Decreased appetite
How common is SAD?
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.
This 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.
What causes 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.
How can I tell if I have SAD?
It is very important that you do not diagnose yourself. If you have symptoms
of depression, see your doctor for a thorough assessment. Sometimes physical
problems can cause depression. But other times, symptoms of SAD are part of a
more complex psychiatric problem. A health professional should be the person to
determine the level of depression and recommend the right form of treatment.