Seasonal Affective Disorder, or SAD, is a type of depression that is normally triggered by a decrease in sunlight. People who experience SAD feel considerably better about themselves in the summer than they do in the winter.
Close to 25 percent of Canadians experience some degree of “winter blues.” Between two and five percent suffer from depression significant enough to be classified as SAD. Women (particularly those between 20 and 40), are twice as likely as men to experience the condition.
What Are The Symptoms?
The symptoms of SAD usually begin in October or November, when the days grow shorter. They increase in severity throughout the winter, reaching a peak in January and February before subsiding in March or April when the length of daylight increases. The symptoms include feelings of sadness, excessive sleeping, increased desire for sugary and starchy foods (especially comfort foods like chocolate and pasta), weight gain, loss of libido and loss of desire to socialize.
Children and teenagers also suffer from SAD or winter blues. Their symptoms may include grades that fall in the winter (and rise again in the spring), and/or a decrease in the quality of relationships with teachers and peers. Researchers in northern climates have found that as many as 90 percent of 12 to15-year-olds report a lack of energy, depressed mood, or need for more sleep during winter.
What Causes SAD?
Researchers believe that SAD is caused by an increase in the brain’s daytime output of the sleep hormone, melatonin. Melatonin is secreted by the pineal gland (a small structure at the base of the brain), when the retinas of the eyes respond to an absence (or near-absence) of light. For most adults, melatonin is typically released between 9 and 11 p.m., when we begin to "wind down" in preparation for sleep. Melatonin levels continue to increase throughout the night, peaking between 3:00 and 5:00 a.m., then gradually drop off as morning approaches.
People with SAD or winter blues continue to produce melatonin after waking. Scientists believe that the lack of early morning sunlight during the winter months results in the body not receiving the cue that nighttime has ended. The body therefore continues to produce melatonin, giving rise to feelings of sluggishness and fatigue, when everything is an effort, and the desire to rest or sleep or rest can be overwhelming.
Who Gets SAD?
The frequency of SAD and winter blues rises as distance from the equator increases, and as hours of daylight decline with the onset of winter. In the United States, for example, incidence of SAD and winter blues is 10 times more common in the northern states than in the south. Here in Canada, incidence is high due to our northern location on the planet. Weather patterns may also affect the frequency, with cities that experience prolonged cloud cover and/or rainy climates in fall and winter - such as Vancouver and Halifax - reporting higher incidences of both SAD and winter blues.
The Power of Light Therapy
Light therapy, also known as phototherapy, involves the use of a bright light source that shines light at the user's eyes. The light is used during the waking hours, as the eyes must be open to record the light. Although the precise mechanism of light therapy isn't completely understood, it is known to suppress the production of melatonin. Light therapy is also thought to increase the level of serotonin - the “feel good” chemical produced by the brain - in much the same manner as SSRI antidepressants.
Light therapy has been researched at leading institutions worldwide for over 20 years, and has been found to be completely safe. It is believed by most health professionals to be more effective for SAD than antidepressant therapy.
Treatment usually consists of 15 - 60 minutes of light, as early as possible after waking in the morning. It is not necessary to stare at the light, and users are encouraged to perform other tasks such as reading, eating, applying makeup, watching television, exercising or working at a computer while receiving light therapy.
Portable Treatment
Early light therapy devices, known as light boxes or "SAD lights" used a fluorescent light source and were large and cumbersome. A smaller, portable light therapy device, the Litebook®, is now available at London Drugs. The Litebook® uses a different form of light source, the white light emitting diode (LED), which requires one-tenth of the power used by fluorescent light sources. The unit emits virtually no heat and, most importantly, the light emitted peaks within the exact wavelength shown to be most effective for suppressing melatonin. This results in a shorter treatment time of 15 to 20 minutes a day.
While light therapy is considered safe and effective, it is important that you consult your doctor if you have a history of eye disease, or if you have not yet received a diagnosis of SAD or winter blues.
Colleen's Story
Every October, Colleen felt her body go through changes. While the summer months saw her running in the mornings, enjoying her work and finding the energy to entertain friends in the evenings, the winter months were another story altogether. Colleen found herself sleeping more, craving carbohydrates such as pasta and bread, and becoming easily irritated by family and friends.
By December, the 33-year-old public relations executive felt thoroughly depressed. Even the simplest of tasks seemed impossible to complete. Although she made the effort to exercise regularly, Colleen couldn't maintain her summer weight and was dismayed by the overly snug fit of her winter wardrobe.
“I felt like a hibernating bear,” she explains. “My brain felt fuzzy - like a radio producing static because it was not tuned into the right station.”
After going though the cycle for ten years, Colleen finally sought help. Her doctor diagnosed her with Seasonal Affective Disorder (SAD) and prescribed light therapy - a means of coaxing the brain to halt its daytime production of melatonin.
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