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What is Seasonal Affective Disorder?
Seasonal Affective Disorder (SAD) is a serious form of depression that occurs at the same time each year. Researchers have identified two types of SAD. The most common type, known as "winter depression," usually begins in the late fall to early winter months and ends in spring. SAD can also occur in the summer, known as "summer depression."
Surveys estimate that four to six percent of the general population experience SAD. Women with SAD outnumber men four to one. The disorder usually begins in person's early twenties and the risk for developing SAD decreases with age.
What are the symptoms of Seasonal Affective Disorder?
People who suffer from SAD can have the common symptoms of depression such as sadness, anxiety, loss of interest in usual activities, withdrawal from social activities, and an inability to concentrate.Symptoms most common to winter depression include:
- Regularly occurring symptoms of depression (excessive eating and sleeping, weight gain) during the fall or winter months.
- Full remission from depression occur in the spring and summer months.
- Symptoms have occurred in the past two years, with no non-seasonal depression episodes.
- Seasonal episodes substantially outnumber non-seasonal depression episodes.
- A craving for sugary and/or starchy foods.
- Irritability and desire to avoid social contact
- Sleep problems, a desire to oversleep and difficulty staying awake but, in some cases, disturbed sleep and early morning wakening
- Feeling of fatigue and inability to carry out normal routine
- Overeating or a craving for carbohydrates and sweet foods, usually resulting in weight gain
- Depression or feelings of misery, guilt and loss of self-esteem, sometimes hopelessness and despair, sometimes apathy and loss of feelings
- In some sufferers, extremes of mood and short periods of hypomania (overactivity) in spring and autumn.
- Shows signs of a weakened immune system during the winter, and are more vulnerable to infections and other illnesses.
How is Seasonal Affective Disorder diagnosed?
Physicians can diagnose SAD based on a set of standards developed by the American Psychiatric Association. Your physician can determine if you are suffering from depression and if this depression is Seasonal Affective Disorder.
What causes Seasonal Affective Disorder?
The exact cause of SAD is unknown, but researchers suspect changes in the availability of sunlight plays an important role. Winter depression becomes increasingly more common the farther people live north or south of the equator. Episodes of winter depression also tend to be longer and more severe at higher latitudes.
How is Seasonal Affective Disorder different from the holiday blues?
Many people use the expression "holiday blues" to refer to a sadness or depression occurring during winter or the holiday season. This term should be differentiated from SAD. The holiday blues are related to psychosocial factors such as increased family obligations, isolation, decreased exercise, expectations that one should feel good, or association of the holidays with early memories and possible unresolved childhood conflicts. In contrast, SAD is a subtype of a major depressive disorder (or bipolar disorder) with seasonal patterns and appears to be more biological in origin.
How is winter depression treated?
Research now shows that light therapy, or exposure to light, is an effective treatment for winter depression. Light therapy is administered by a 10,000-lux light box, which contains white fluorescent light tubes covered with a plastic screen that blocks ultraviolet rays. Full-spectrum light is not necessary. The patient sits in front of the box with his or her eyes open, but should not look directly into the light. The therapy begins with daily sessions of 10 to 15 minutes, which are gradually increased to 30 to 45 minute sessions. Ninety minutes of exposure per day is often prescribed. The therapy typically continues until spring.
When should light therapy by prescribed?
A diagnosis has been made by a physician. The patient is not suicidal. There are medical reasons to avoid the use of antidepressants. Patient has no history of significant negative effects to light therapy. The patient requests light therapy. An experienced practitioner deems that light therapy is indicated.
How quickly does light therapy work?
Most people notice improvement in 2 to 4 days. In some cases, symptoms may not improve for several weeks. If symptoms are worsening or do not improve after 4 to 6 weeks of therapy, see your physician. You may require a change in treatment.
What other forms of treatment are available?
Treatments that may be helpful for SAD but require further testing include:
- Medications (fluoxetine, propranolol, d-fenfluramine, moclobemide, tranylcypromine, bupropion and others)
- Counseling (especially interpersonal psychotherapy and cognitive therapy)
Other Possible Diagnosis
Humans and animals generally have innate sleep-wake cycles close to but not exactly 24 hours. They depend on the daily light-dark cycle to keep their circadian rhythms to a regular 24 hours. If a human is left in a room with no light-dark cues, he or she will gradually shift into a sleep-wake cycle that is not exactly 24 hours long. Body temperature and the secretion of the hormone melatonin follow the daily cycle.
Other factors, such as work schedule can modify the sleep-wake cycle in humans. The autonomous cycle length varies at different periods in the life span. Adolescents often have an innate cycle longer than 24 hours so that they have the desire to stay up late and sleep in when it is time to get up. The innate cycle then shifts closer to 24 hours for adults, but for the elderly, the autonomous sleep-wake cycle may be shorter than 24 hours resulting in evening tiredness, sleep difficulty and waking too early.
Individuals who have more severe difficulty with the timing of their sleep-wake cycle may have either Delayed Sleep Phase Disorder (difficulty falling sleep and the urge to sleep late) or Advanced Sleep Phase Disorder (tiring too early and waking too early) Both conditions can be treated with bright light. However, the proper timing of the exposure to light and darkness is more critical than it is for SAD. In these conditions, improperly timed light and dark exposure can make the problem worse, not better.
Jet Lag and Shift Work
In the cases of jet lag or shift work, the individual does not have a disorder, but is reacting to externally induced changes in the sleep-wake cycle. Traveling west to east over three or more time zones is the most difficult shift. Large forced changes in the timing of sleep periods can lead to irritability and decreased alertness. Many people can deal with this by getting extra rest while traveling or by switching to a job with a more regular schedule.
However, for those who must deal with frequent sleep timing changes, one may use a special calculator to help determine the timing for exposure to light and darkness just before and during travel or shift change. If one calculates the timing wrong, one may actually make the time phase shift worse instead of better. A travel kit can consist of a calculator, a light visor and special extra dark glasses. Some use small timed doses of Melatonin to achieve the same purpose.
SAD is recognized in the DSM-IV (The American Psychiatric Association's diagnostic manual) as a subtype of major depressive episode. The classic major depression involves decreased appetite, decreased sleep, and often, poor appetite and weight loss. It has long been recognized that some depressed individuals had a "atypical depression" with increased sleep and appetite along with decreased energy. Some, but not all of these atypical individuals also had a seasonal pattern.
Some people with winter depression also have mild or occasionally severe manic mood swings in the spring and summer. If these episodes are severe, the individual might be diagnosed with Bipolar Disorder. (formerly called manic depressive illness)