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Seasonal Affective Disorder

  • Definition

    In its most common form, SAD is a serious depression that recurs each year at the same time, starting in the fall or winter, and ending in the spring. Some of the symptoms typical of depression are sadness, anxiety, irritability, inability to concentrate, withdrawal into solitude and loss of interest in life. Other symptoms are unusual sleep patterns, increased appetite and weight gain. Lethargy (feeling extremely tired) is such an important feature of the disorder that the term "Seasonal Energy Syndrome" has been proposed.


    A sunny disposition, by definition, is a happy one, and a wintry atmosphere is cheerless. Many people become somewhat sluggish or gloomy as the days grow short; the annals of the Far North tell repeatedly of cabin fever in the winter and elation under the midnight sun. For some, the winter mood change is clinical depression. . It was first noticed long ago, but had no accepted name until the early 1980s, when researchers at the National Institute of Mental Health began to call it seasonal affective disorder (SAD).

    People with SAD not only experience symptoms of depression, but often have a leaden feeling in their arms and legs, cravings for carbohydrates, an increase in weight, and an increase in the amount of food eaten. Unlike typical depression, people with SAD tend to increase the amount they sleep.

    More than three-quarters of all sufferers are women, and most are in their 20s, 30s and 40s. People are slightly more likely to have SAD if a family member has it. High rates of nonseasonal depression and alcoholism are also found in these families.

    People who suffer from SAD experience a predictable pattern: the downturn typically begins as daylight hours dwindle in the fall; symptoms become more severe in January or February, and then symptoms lift as the Vernal Equinox approaches.

    The prevalence of SAD increases as you head north from the equator. Studies indicate that about 1 or 2 percent of all people who live in Florida suffer from the disorder, compared with more than 5 percent in Maryland and a fully 10 percent in New Hampshire.

    Taken together, the twin trends of season and latitude strongly suggest a link between SAD and short periods of daylight.

    Four to 9% of people have SAD with almost 20% of people experiencing some symptoms of the disorder.


    In people who suffer from SAD, the short daylight hours of winter seem to play havoc with the body's clock, somehow upsetting their circadian or normal biological rhythms that influence sleepiness, hunger and other physiological and psychological functions. There are three main theories to explain this disruption:

    Melatonin. Most researchers have focused on this hormone, which reaches its highest blood levels between dusk and dawn. It may be that SAD stems from an overproduction of melatonin during the long winter nights. This theory is supported by studies showing that effective light therapy stops the flow of melatonin. Recently, news reports have suggested that taking melatonin pills might actually relieve SAD, but this has not yet been proven.

    serotonin. Production of this chemical wanes in the winter. Deficiency is known to cause depression, as well as a craving for carbohydrates, another symptom of SAD. Studies show that light therapy increases blood levels of serotonin.

    Eye abnormalities. Preliminary evidence suggests that the eyes of people with SAD are less sensitive to light and never fully adjust to dim winter days as normal eyes do. That could disrupt the body clock by making short days seem even shorter.


    Light therapy, also called phototherapy, is considered the standard treatment of SAD. The use of bright light as a way to improve lethargy and gloom has been known for thousands of years but explored systematically only in the past decade. The device most often used today is a bank of white fluorescent lights, mounted on a metal reflector and shielded with a plastic screen. Known as light boxes, these are increasingly available for purchase by those who experience SAD. Light therapy with a form of talk therapy (cognitive behavioral therapy) may be more helpful than light therapy alone.

    Although there have been no controlled studies, SAD can be effectively treated with antidepressant drugs, but these medications often cause an increase in appetite and drowsiness.


    How do you know this is Seasonal Affective Disorder?

    How serious is it or could it become?

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    What about phototherapy? Where can I purchase a light box?