Definition
Seasonal affective disorder (SAD) is a form of depression most often associated with lack of daylight in extreme northern and southern latitudes from the late fall to the early spring.
Description
Although researchers are not certain what causes seasonal affective disorder, they suspect that it has something to do with the hormone melatonin. Melatonin is thought to play an active role in regulating the "internal body clock," which dictates when humans feel like going to bed at night and getting up in the morning. Although seasonal affective disorder is most common when light is low, it may occur in the spring, which is often called reverse SAD.
Causes & symptoms
The body produces more melatonin at night than during the day, and scientists believe it helps people feel sleepy at nighttime. There is also more melatonin in the body during winter, when the days are shorter. Some researchers believe that excessive melatonin release during winter in people with SAD may account for their feelings of drowsiness or depression. One variation on this idea is that, during winter, people's internal clocks may become out of sync with the light-dark cycle, leading to a long-term disruption in melatonin release. Another possible cause of SAD is that people may not adjust their habits to the season, or sleep more hours when it is darker, as would be natural.
Seasonal affective disorder, while not an official category of mental illness listed by the American Psychiatric Association, is estimated to affect 10 million Americans, most of whom are women. Another 25 million Americans may have a mild form of SAD, sometimes called the "winter blues" or "winter blahs." The risk of SAD increases the further from the equator a person lives.
The symptoms of SAD are similar to those of other forms of depression. People with SAD may feel sad, irritable, or tired, and may find themselves sleeping too much. They may also lose interest in normal or pleasurable activities (including sex), become withdrawn, crave carbohydrates, and gain weight.
Diagnosis
Doctors usually diagnose seasonal affective disorder based on the patient's description of symptoms, including the time of year they occur.
Treatment
The first-line treatment for seasonal affective disorder is light therapy (also known as phototherapy). The most commonly used phototherapy equipment is a portable lighting device known as a light box. The box may be mounted upright to a wall, or slanted downward toward a table. The patient sits in front of the box for a pre-prescribed period of time (anywhere from 15 minutes to several hours). Some patients with SAD undergo light therapy sessions two or three times daily, and others only once. The time of day and the number of times treatment is administered depend on the physical needs and lifestyle of the patient. Light therapy treatment for SAD typically begins in the fall months as the days begin to shorten, and continues throughout the winter and possibly the early spring.
The light from a slanted light box is designed to focus on the table it sits upon, so patients may look down to read or do other sedentary activities during therapy. Patients using an upright light box must face the light source (although they need not look directly into the light). The light sources in these light boxes typically range from 2,500 to 10,000 lux (in contrast, average indoor lighting is 300 to 500 lux; a sunny summer day is about 100,000 lux).
Patients with eye problems should see an ophthalmologist regularly both before and during light therapy. Because some UV rays are emitted by the light boxes used in phototherapy, patients taking photosensitizing medications and those who have sun-sensitive skin should consult with a health care professional before beginning treatment. Patients with medical conditions that make them sensitive to UV rays should also see a doctor before starting phototherapy.
Light therapy appears to be safe for most people. However, it can cause side effects of eyestrain, headaches, insomnia, fatigue, sunburn, and dry eyes and nose in some patients. Most of these effects can be managed by adjusting the timing and duration of light therapy sessions. A strong sun block and eye and nose drops can alleviate the others.
Recently, researchers have begun testing whether people who do not completely respond to light therapy can benefit from tiny doses of the hormone melatonin to reset the body's internal clock. Early results look promising, but the potential benefits must be confirmed in larger studies before this type of treatment becomes widely accepted.
Allopathic treatment
Like other types of mood disorders, seasonal affective disorder may also respond to medication and psychotherapy. Common drugs prescribed for mood disorders are:
- Selective serotonin reuptake inhibitors (SSRIs), such as fluoxetine (Prozac), paroxetine (Paxil), and sertraline (Zoloft)
- Monoamine oxidase inhibitors (MAO inhibitors), such as phenelzine sulfate (Nardil) and tranylcypromine sulfate (Parnate)
- Lithium salts, such as lithium carbonate (Eskalith), often used in people with bipolar mood disorders, are often useful with SAD patients who also suffer from bipolar disorder (excessive mood swings; formerly known as manic depression)
A number of psychotherapy approaches are useful as well. Interpersonal psychotherapy helps patients recognize how their mood disorder and their interpersonal relationships interact. Cognitive-behavioral therapy explores how the patient's view of the world may be affecting mood and outlook.
Expected results
Most patients with seasonal affective disorder respond to light therapy and/or antidepressant drugs. Others respond to sleeping more hours in a dark room. Some researchers estimate that as much as 9.5 hours of sleep are important in winter months and that sleeping more will increase natural melatonin.
Key Terms
- Cognitive behavioral therapy
- Psychotherapy aimed at helping people change their attitudes, perceptions, and patterns of thinking.
- Melatonin
- A naturally occurring hormone involved in regulating the body's "internal clock."
- Serotonin
- A chemical messenger in the brain thought to play a role in regulating mood.
Symptoms of Seasonal Affective Disorder (SAD)
| Symptoms |
|---|
| Increased sleep |
| Depression |
| Lethargy |
| Weight gain |
| Carbohydrate cravings |
| Decreased sex drive |
| Avoidance of social interaction |
| Difficulty performing daily tasks |
| Crying fits |
| Suicidal thoughts |
Further Reading
For Your Information
Books
- Peters, Celeste A. Don't Be SAD: Your Guide to Conquering Seasonal Affective Disorder. Calgary, Alberta: Good Health Books, 1994.
Periodicals
- Anderson, Janis L., and Gabrielle I. Warner. "Seasonal Depression." Harvard Health Letter (February 1996): 7-8.
- "Winter Depression: Seeing the Light." The University of California Berkeley Wellness Letter (November 1996): 4.
Organizations
- National Depressive and Manic Depressive Association. 730 N. Franklin Street, Ste. 501, Chicago, IL 60610. (312) 642-0049.
- National Institute of Mental Health. Mental Health Public Inquiries, 5600 Fishers Lane, Room 15C-05, Rockville, MD 20857. (301) 443-4513. (888) 826-9438. http://www.nimh.nih.gov.
Gale Encyclopedia of Alternative Medicine. Gale Group, 2001.
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