What Is Seasonal Affective Disorder?
Have you ever noticed how a gray, rainy day makes you feel gloomy and tired, but a sunny day can leave you feeling cheerful and energized? Well, there's a scientific reason for this. Insufficient exposure to sunlight has been associated with low levels of melatonin and serotonin, carbohydrate craving, weight gain, and sleep disturbance.
Some of you may have also noticed that you find a seasonal fluctuation in your moods, feeling depressed only in the winter months. Take a look at your calendar and you'll soon see why. Each year on June 21 we experience the summer solstice, the longest day of the year. With our longest hours of sunlight in the middle of summer it's no wonder we're happier this time of year. After this date, however, the days progressively get shorter until the winter solstice on December 21, the shortest day. Is it any accident then that so many of us run for the hills when the holidays roll around? With our serotonin in such short supply, the added stresses of living up to our images of the picture-perfect holiday are just too much. The medical term for the season-long malaise that we fall into is seasonal affective disorder, or SAD.
Signs and Symptoms of Seasonal Affective Disorder
The symptoms of SAD occur cyclically with a return of symptoms each year during the winter months. These symptoms tend to be the atypical symptoms of depression, including:
- increased sleep;
- increased appetite and carbohydrate cravings;
- weight gain;
- interpersonal difficulties (especially rejection sensitivity), and
- a heavy, leaden feeling in the arms or legs.
Causes of Seasonal Affective Disorder
SAD is believed to be caused by a disturbance in the normal circadian rhythm of the body. Light entering through the eyes influences this rhythm. When it is dark, the pineal gland produces a substance called melatonin which is responsible for the drowsiness we feel each day after dusk. Light entering the eyes at dawn shuts off the production of melatonin. During the shorter days of winter, when people may rise before dawn or not leave their offices until after sunset, these normal rhythms may become disrupted, producing the symptoms of SAD.
There is also evidence linking SAD to a reduced amount of the neurotransmitter serotonin. Serotonin is the feel-good substance that is increased by antidepressants called selective serotonin reuptake inhibitors (SSRIs). This decrease in serotonin production may be responsible for many of the symptoms of SAD, such as depression and carbohydrate cravings.
Diagnosis of Seasonal Affective Disorder
There is no laboratory test for SAD. It is diagnosed based upon a person's symptom history using criteria set forth by the Diagnostic and Statistical Manual of Mental Disorders (DSM-IV). The DSM-IV does not consider SAD to be a separate disorder. Instead it is a “specifier” of Major Depressive Episode. In order to be diagnosed with SAD a person must first of all meet the criteria for a Major Depressive Episode:
A. At least five of the following symptoms have been present during the same two-week period, nearly every day, and represent a change from previous functioning. At least one of the symptoms is either (1) depressed mood or (2) loss of interest or pleasure.
NOTE: Do not include symptoms that are clearly due to a general medical condition, or mood-incongruent delusions or hallucinations.
- Depressed mood (or alternatively can be irritable mood in children and adolescents).
- Markedly diminished interest or pleasure in all, or almost all, activities.
- Significant weight loss when not dieting or weight gain or decrease or increase in appetite.
- Insomnia or hypersomnia.
- Psychomotor agitation or retardation.
- Fatigue or loss of energy.
- Feelings of worthlessness or excessive or inappropriate guilt.
- Diminished ability to think or concentrate, or indecisiveness.
- Recurrent thoughts of death (not just fear of dying), recurrent suicidal ideation without a specific plan, or a suicide attempt or a specific plan for committing suicide.
B. The symptoms are not better accounted for by a mood disorder due to a general medical condition, a substance-induced mood disorder, or bereavement (normal reaction to the death of a loved one).
C. The symptoms are not better accounted for by a psychotic disorder like schizoaffective disorder.
If these criteria fit, the follow criteria would also need to be met to obtain a seasonal pattern specifier:
A. Regular temporal relationship between the onset of major depressive episodes and a particular time of the year (unrelated to obvious season-related psychosocial stressors)
B. Full remissions (or a change from depression to mania or hypomania) also occur at a characteristic time of the year
C. Two major depressive episodes meeting criteria A and B in last two years and no nonseasonal episodes in the same period
D. Seasonal major depressive episodes substantially outnumber the nonseasonal episodes over the individual's lifetime