Seasonal Affective Disorder

As the days get shorter, the leaves turn colour and the sky gets a bit cloudier, there's no denying that fall is here with winter fast on its heels.

While this does mean the coming of the ski season, many people say they feel less motivated when the weather gets cooler and for some, the change in seasons can bring on depression.

This seasonal depression is known as seasonal affective disorder (SAD) and those who experience it tend to get recurring depression during fall and winter months with normal mood returning during the spring and summer.

SAD is a mood disorder that is related to seasonal variations of light. Just as sunlight affects the activities of animals, seasonal depression may be the result of light exposure in humans. Our body clocks are affected by the seasons and for some, get out of step with the requirements of daily functioning.

Typically, January and February are the most difficult months for individuals experiencing SAD, but for many, symptoms begin as early as October and can last until May.

Symptoms in SAD are the same as the usual symptoms of depression, feelings of sadness, changes in appetite and sleep pattern, loss of interest in activities, decreased libido and social withdrawal. However, in order for seasonal depression to be diagnosed, symptoms must fully dissipate during the spring and summer months and must be recurring each winter with no non-seasonal depression.

Usually, SAD involves mild to moderate symptoms that do not require hospitalization, but in some cases the depression can be severe.

Although seasonal variations in light are thought to be involved in SAD, there is also likely a genetic component to this condition. Many people with seasonal depression have a family history of psychiatric illness, usually depression.

Light therapy is a first line treatment for seasonal affective disorder and has shown to be very effective. In this therapy, patients receive a phototherapy lamp with a bulb emitting a colour temperature somewhere between 3,000 and 6,500 degrees Kelvin. The bulb is encased in a box with a diffusing lens that filters out the potentially harmful UV radiation. Patients then spend certain amounts of time each day sitting with the lamp turned on at eye level. There are several different models of light available locally and they can also be rented at some pharmacies.

Light therapy works by suppressing the brain's secretion of melatonin, which has been found to be involved in seasonal depression. The amount of time each person needs to be exposed to the therapeutic light will depend on the severity of the depression and should be prescribed by a physician.

Studies show that this therapy leads to full remission in 50 to 80% of those who use it throughout the winter months. In cases where phototherapy doesn't work, an antidepressant medication may prove effective either on its own or in combination with the light exposure.

For mild symptoms, spending time outdoors during the day or increasing the amount of sunlight exposure through windows can be helpful. In fact, one study found that an hour long walk in winter sunlight was just as effective as two and a half hours under bright artificial light.


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