Coming Out of the Cold: Treating Your Seasonal Affective Disorder

Between six and 10 percent of the population suffer from seasonal depression during the winter months -- but there are ways to end it


The days are growing shorter and colder in the Northern hemisphere. And some people are feeling gloomier. Seasonal affective disorder (SAD) is the seasonal depression that affects between six percent and 10 percent of the population generally during the winter months. Though many people may feel a bit blue during the short, cold days of winter, for others, the symptoms are more serious. SAD is a genuine form of depression and a recognized psychiatric disorder, with a specific symptom set and treatment requirements.

SAD can affect the sufferer in much the same way as clinical depression. Like depression, seasonal affective disorder can range from mild to severe. It appears to be much more common in higher latitudes than in lower ones and is more common in North America, where the prevalence is higher than in other parts of the world, and twice as high as in Europe.

Seasonal affective disorder can make life extremely unpleasant for the sufferer, but the good news is that it is treatable. Though the symptoms of SAD tend to go away during the warmer months of the year, there's no reason to suffer from it if you don't have to.


Seasonal affective disorder is considered a form of recurrent major depressive disorder by the American Psychological Association. It usually begins in the fall, with symptoms worsening during the winter months and improving in the spring and summer.

Most of the symptoms of SAD are the same as those of "regular" depression: sad or hopeless feelings; a lack of energy; changes in sleep and eating patterns; inability to concentrate, especially in the afternoon; social withdrawal; irritability; and loss of interest in previously enjoyable activities. In SAD, as opposed to non-seasonal depression, overeating with weight gain and sleeping more than usual are two of the more common symptoms. Occasionally a "reverse" SAD can occur, with people experiencing symptoms during the summer months rather than the winter, but this form is rare.


Though it might seem intuitive that the cause of SAD might simply be the cold temperatures and relative restriction in the types of activities that one can do outside in Northern climates, it's actually more likely that SAD has to do with the lack of light in winter months. When days get shorter, we are exposed to much less natural light, which can affect levels of the neurotransmitters (brain chemicals) involved in mood and depression.

We all have a biological "clock," made up of cells in an area of the brain called the suprachiasmatic nucleus, which keeps us more or less on a 24-hour cycle. However, our biological clocks seem to need sunlight to stay set on a regular cycle. When people are kept in the dark, their natural cycles tend to extend: over time, the sleep-wake cycle becomes closer to 25 hours if it does not have a cue to reset it each morning.

Early morning light is believed to be what "resets" the clock to keep it on a 24-hour period. But the other half of the equation is our genes. "Clock genes" are expressed in the brain and help maintain our natural rhythm. It's known that the circadian rhythm is affected in mood disorders like major depression and bipolar disorder, since sufferers can have disrupted sleep-wake cycles. There also seems to be some genetic predisposition to having disrupted clock genes.

This internal clock is intimately connected with the serotonin systems of the brain. Serotonin is the brain chemical that is reduced in people who suffer from depression and anxiety, and it is the one targeted by the popular class of antidepressants, the selective serotonin re-uptake inhibitors (SSRI), that include Prozac.

Mice without serotonin receptors have significantly altered circadian rhythms, and in humans, the production of serotonin is markedly reduced during winter months, and highest in long periods of bright light. Other studies have shown that serotonin is less available to circulate the brain during the winter months compared to summer months. This is because during the winter months and under reduced light availability, serotonin is bound more strongly by the serotonin transporter, the molecule that clears serotonin away from the synapse so that it can be reused.

Some authors have suggested that because of the neurological overlap between the light-dark cycle and the brain chemicals involved in depression, problems with circadian rhythm can be a strong marker for mood disorders. Though the mechanisms that explain SAD are not straightforward, researchers are starting to understand the connections in more detail, which will ultimately allow for better, more targeted, treatment methods.


Because SAD involves more than one system in the brain (the light-mediated clock and the serotonin network), treatments tend to target one or the other. Tandem treatments are sometimes recommended for SAD and may be more effective than a single method by itself. Light therapy, antidepressant medications, and psychotherapy are all used to treat SAD. It is important to speak with your doctor about which treatment method is right for you, based on the severity of your SAD, health status, and the side effects of the treatments.

Light Therapy

Exposure to light, or light therapy, is a basic treatment for seasonal affective disorder. Typically, light therapy involves sitting in the glow of a light box which emits a spectrum of light mimicking daylight. A person typically places the light box in a place where they sit for periods of time, so the light enters the eyes indirectly. As with the sun, it is important not to stare at the light box directly.

Presented by

Alice G. Walton, PhD, is a health journalist and an editor at The Doctor Will See You Now.

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