Winter Depression
Q: As winter approaches, large numbers of people, particularly those living
in northern or rainy climates in the United States and Canada, will
complain of feeling tired or sluggish. Many individuals simply accept
these feelings as normal responses to cold, dreary, winter days, and
look forward to summer. While few people with winter-onset changes in
mood or energy levels might actually receive a diagnosis of winter
depression, seasonal changes in mental and physical function may
significantly affect a person's general quality of life.
What is Winter Depression?
A:Winter depression is often referred to as seasonal affective disorder,
or SAD. Under the official diagnostic criteria from the American
Psychiatric Association, winter depression is diagnosed as a subtype of
either major depression or bipolar depression. The American Psychiatric
Association criteria recognize two broad types of depression, known as
typical depression and atypical depression. Winter onset depression is
generally considered to be an atypical type of depression, because
individuals who have it tend to sleep more, eat more, gain weight, and
have decreased activity. In essence, they become somewhat physically
and mentally sluggish. Of note, many individuals notice increased
craving for carbohydrates (including sweets) during winter
depression. Some scientists think that winter depression might be a
reasonable evolutionary adaptation to winter, similar to the more
intense increase in appetite, body weight, and sleep in hibernating
animals. However, with the development of artificial lighting and
reliable heating, most people no longer have the opportunity to cut back
on work during the winter months.
In my opinion, winter depression is an unfortunate term for winter-onset
changes in mood and energy, particularly because physical symptoms and
apathy seem much more prominent than overt depressed mood and
sadness. However, like all types of depression and other mental
illnesses, winter depression is a complex condition involving the brain
and other organs.
What Causes Winter Depression?
The exact causes of winter depression are unclear, but the serotonergic
neuron system in the brain seems to be affected. Shortened day length,
and perhaps decreased sunlight intensity are thought to be major factors
influencing the severity of symptoms, so that people who live further
north in North America tend to have more symptoms. Recent evidence
suggests that changes in ion density (invisible charged particles in the
atmosphere) might also be important. Altered vitamin D production
during the winter, along with changes in exercise, and changes in
temperature may be important in some cases. Dietary factors, such as
fish oil consumption might also be involved. Changes in melatonin
levels do not appear to be very important in winter depression.
How is Winter Depression Treated?
As with all forms of serious depression, such as depression associated
with marked impairments in functioning, or with suicidal feelings, a
health care professional should be consulted. The most effective
treatment for winter depression seems to be exposure to bright light
early in the morning, although some people respond better to light later
in the day. A light intensity of 2500 lux for about 2 hours seems to be
sufficient in most cases. Various manufacturers sell portable and
full-sized light boxes designed for use as light therapy. Some
insurance companies pay for light boxes, but light treatment doesn't
seem to be routinely compensated. The available research indicates that
getting up early in the morning might be a critical component of the
success of light therapy, so sleeping late and then