Psychology Information Online Homepage

Children Homepage

National Directory of Psychologists - Locate a Local Psychologist

Articles by Psychologists

Forensic Psychology

Subject Index of Topics

What is a Psychologist?

How to Select a Psychologist

Information About Psychological Problems

Information About Psychological Treatment

Psychology Bookstore

Frequently Asked Questions about Psychology


List your practice in the National Directory of Psychologists

Publish Articles Online

Locate Continuing Education Programs

Psychology Jobs

Market Your Practice

Professional Resource Directory


Psychology Careers

Graduate Education

Licensing Information

Seasonal Affective Disorder

Seasonal affective disorder is not yet accepted as a distinct psychological disorder. Rather, other mood disorders (major depression, bipolar depression, dysthymia) can be qualified with a "seasonal pattern specifier." What this means, is that the primary mood disorder appears to vary according to the seasons of the year. Whether this represents a distinct psychological disorder, or simply that seasonal variations in weather and sunlight can trigger a depressive or manic episode, remains to be clarified. But, for the many people who become depressed during the winter months, seasonal affective disorder provides a rational explanation, and appropriate treatment, for a chronic and debilitating psychological problem.

Features of Seasonal Affective Disorder

The primary feature of seasonal affective disorder is a pattern of depressive or manic episodes that occurs with the onset of the winter months. As the days become shorter, and the weather colder, there is an increase in vegetative depressive symptoms. Individuals eat more, crave carbohydrates, sleep more, experience chronic fatigue and gain weight. In pronounced cases, significant social withdrawal occurs as well. Some have described the pattern as a hibernation during the winter months. 

The second phase of the disorder, is the tendency for these symptoms to abate once the days become longer and warmer in the Spring.  Again, the hibernation analogy works well. Finally, this pattern of seasonal depression must be present for at least two consecutive years, without any occurrences of non-seasonal depression Researchers are still trying to determine if this is a separate disorder, or simply the manifestation of recurrent major depression or another mood disorder in a cycle pattern. Is the depression caused by a decrease in sunlight, by colder weather, or by the increased isolation and stress of coping with the winter months? There is some indication that sunlight, entering through the retina, stimulates the production of chemicals in the brain that have an antidepressant effect, but many questions remain unanswered.  Because both biological and physical factors appear to play a role in most depression, it is difficult to develop an experimental study that will control for all other relevant variables to produce definitive answers. Meanwhile, those who become depressed in the winter months want to know what they can do to combat this depression. 

Demographics and Statistics

Seasonal affective disorder, occurring during the winter months, appears to vary according to latitude, age and sex. At higher latitudes (farther North), there are more cases of seasonal affective disorder. Since sunlight decreases with higher latitude, the length of day appears to be a factor. It also tends to be colder in the winter, with harsher conditions and storms, as you travel farther North.

Younger people appear to be diagnosed with seasonal affective disorder more frequently than older people.  This may be related to a tendency of younger people to look at seasonal factors as causal in their depression, or it may suggest a biological pattern related to aging. 

Women are far more likely to be diagnosed with seasonal affective disorder than men. There are many possible reasons for this.  Women with small children are more likely to be isolated during the winter months, while those with careers are not. Men are less likely than women to be home caretakers for small children. Statistics are not available regarding differential rates between working and non-working women. Also, women have higher rates of major depression as well. It is not clear whether the higher rates of seasonal affective disorder are simply part of that gender difference, rather than being evidence of another disorder. 


Light therapy or photo therapy has been recommended for seasonal affective disorder. This is based on the assumption that decreased exposure to full spectrum light may be responsible for chemical changes that trigger depression in some people.  The treatment requires the person to sit under a full spectrum light for several hours per day, throughout the winter months. As an alternative, individuals are encouraged to take walks outdoors whenever possible (depending on weather conditions).  More recently, some studies have suggested that the full spectrum is not necessary, but that it does require exposure to bright light conditions for several hours per day. 

In addition to the light therapy, other more traditional treatment of depression is also recommended, including both psychotherapy and antidepressant medication. Some people have found that a short winter vacation to a warmer climate helps as well. The other treatment methods are described elsewhere on this site.

Of course, most of us feel better after a vacation. And, taking a daily walk in the winter would certainly help reverse the impact of isolation or "cabin fever" many people experience in the winter. Even the recommendation to spend several hours per day under the lights, also recommends that the person do something productive while receiving exposure, such as reading. It is not possible to evaluate independently the effects of these other factors. On the other hand, light therapy is not expensive, and does not appear to be intrusive or potentially harmful.  If the combination of traditional treatment and light therapy appears to be more helpful to some individuals, we might not need to wait for researchers to confirm the existence of seasonal factors in some depression. We can recommend the treatment while we wait for the results of the research.


More Information About Depression