Seasonal affective disorder (SAD) is a type of depression that occurs during certain times of the year, especially in the winter months. Although it is currently unclear exactly how light affects the circadian rhythms or the "body clock" in human beings, studies suggest it is related to serotonin production in the brain. Serotonin, the "feel good" neurotransmitter, is, in turn, the precursor to the hormone melatonin, which affects sleep patterns.
Seasonal affective disorder is more common among people in the north than those in southern areas, with 25 percent of people in the northern United States reporting at least some symptoms of SAD.
For those affected, January and February are the months in which the greatest number of symptoms appear.
The disorder is more common among women than men, usually begins in adulthood, and may last throughout a person's lifetime. Fortunately, only between two and three percent of those affected have symptoms severe enough to require special treatments.
Features of SAD
Seasonal affective disorder usually appears slowly during the fall although it may occur much more quickly beginning in the spring.
As a person's body clock adjusts to diminishing light during the fall and winter months, it will affect everything from hormone production and brain activity to eating and sleeping patterns. In some individuals, these changes may cause depression.
People with SAD may eat or sleep excessively and often crave either sugary or starchy foods, or both. Other symptoms may include having trouble waking in the morning or wanting to nap in the afternoon; feeling sluggish; having a lowered interest in sex or other pleasurable activities;having trouble concentrating; and gaining weight associated with food cravings. In addition, some women will experience a worsening of premenstrual symptoms.
In the spring, some people may also have a rush of energy which can border on mania.
Because the symptoms of SAD usually differ somewhat from other forms of depression, there must be a pattern for two or more years before a proper diagnosis can be made.
In order to diagnose SAD, healthcare providers may ask a series of questions about symptoms, a patient's medical history, and about any alcohol or drug use.
A physician may also perform lab tests to rule out other medical conditions including hormone imbalances, although there are no specific lab tests to identify SAD.
Light Therapy for Seasonal Depression
The most effective treatment for seasonal affective disorder is increased exposure to sunlight or certain types of artificial light.
It is currently unknown what the ideal dose of lighting is, but it is clear that exposure to bright light in the morning and relatively little at night may help to synchronize the body's circadian rhythms.
A 2004 study found that women who got the most light in the morning reported better moods and sleep patterns.
For more severe cases of SAD, antidepressants or psychotherapy may help as well.
Prevention: The Best Medicine
There are several ways to head off SAD without heading to the doctor. These include:
- taking a 30-minute walk outdoors each morning
- eating breakfast near a window
- combining exercise with morning light
- installing bright lights anywhere a great deal of time is spent in the morning, such as in a bathroom
- purchasing broad-spectrum lights, bluish-white compact fluorescents, or halogen bulbs, or a special light box known as a "dawn simulator"
- installing dimmer switches to minimize light exposure after 6 pm.
- eating plenty of Omega-3 fatty acids or taking an herbal remedy such as St. John's Wort
- maintaining regular eating and sleeping patterns
- connecting with family and friends
- practicing relaxation skills such as breathing exercises, meditation, or yoga
A person who suspects she has SAD may contact a physician to see if she is a good candidate for light therapy. Light therapy will typically work within three to four weeks. If it doesn't, or if symptoms are more severe, it may indicate a more serious depressive disorder.
People who have suicidal ideation or thoughts of harming others should seek immediate help from a mental health professional, as SAD can result in long-term depression or even bipolar disorder.