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Teen Health

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Seasonal Affective Disorder (SAD)

"Claire" began her sophomore year in high school eager to make new friends and committed to doing well in her classes. Then, as winter approached and the days grew shorter, Claire noticed that she needed more sleep than usual. Even after sleeping more, she had no energy and felt fatigued, moody, and depressed.

When she tried to write articles for the school paper, something that normally came easy for her, Claire had trouble concentrating. She started to miss deadlines. When it came time to print the newspaper, Claire had no articles to turn in. Over the next two months, friends stopped calling her. When Claire complained that no one invited her to sit with them at football games or attend weekend sleepovers, her parents became concerned.

Over the winter break, Claire had an appointment with her doctor. Claire told her doctor how tired she felt. She said no matter how much she slept, it was never enough to end her fatigue and sad mood. She also mentioned that she had gained weight since August, and that her appetite for carbs, especially chips and cookies, had greatly increased. 

After doing a physical exam, Claire’s doctor ruled out other problems that cause fatigue and mood changes and diagnosed Claire with seasonal affective disorder, or SAD.

What Causes Seasonal Affective Disorder?

Seasonal affective disorder, also referred to as winter or seasonal depression, is a syndrome with depression that starts and ends at the same time each year.

There are two types of SAD:  fall-onset SAD and summer-onset SAD. The fall-onset type, often called "winter depression," is more recognized. With less sunlight during these two seasons, some people who are predisposed to depression may be more likely to develop an episode.  While the neurobiological causes of SAD are not well-established, it is thought that brain areas which regulate mood and operate using the neurotransmitter serotonin may not function properly.  The National Institutes of Health estimates that more than 36 million Americans suffer seasonal depression that occurs in the fall.

Hormones manufactured in the brain that are affected by sunlight exposure may play a role in the development of SAD and its symptoms of depressed mood, fatigue, carbohydrate cravings, and weight gain. Because foods high in carbohydrates (like chips, pretzels, and cookies) boost serotonin, it is thought that they have a soothing effect on the body and mind.

SAD usually starts in young adulthood. It is more common in females than in males. Some teens with SAD have very mild symptoms and just feel out-of-sorts or irritable. Others have more serious symptoms that interfere with relationships and schoolwork.

Because the lack of daylight during wintertime is related to SAD, it is seldom found in countries within 30 degrees of the equator, where the sun shines year round.

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