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Seasonal Affective Disorder Is The Clinical Name For The Winter Blues

Unless you live in a tropical paradise, chances are that some months of the year are gloomier than others. As autumn and winter roll around, the tilt of the Earth pulls us out of sunlight's direct path, leading to colder temperatures, fewer daylight hours, and more time spent inside. For some people, this can also lead to a period of depression that physicians call seasonal affective disorder, or SAD.

The snappy acronym notwithstanding, SAD is no social media trend—it's a real psychological condition with real drawbacks. According to American Family Physician, about 5% of the U.S. population—as many as 1 in 20—experiences SAD in a given year, and in northern latitudes, that number can climb to 10%. SAD is a form of clinical depression, and its symptoms are similar with two differences: they only affect you seasonally (for 40% of the year, on average), and they can make you crave food more, especially carbohydrates.

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So what exactly causes it? That's not clear. Most researchers agree that a lack of sunlight plays a role, especially since light affects circadian rhythms (that is, your internal clock) and vitamin D levels, among other things. But light is probably not the only cause. The lifestyle changes that come with colder weather, like spending less time exercising outside and more time curled up on the couch, can cause a dip in mood, as can the highs and lows of the holiday season.

While antidepressants can help, there's a drug-free solution that's shown to be just as good for some people: light therapy. This unique treatment entails sitting close to a light box that shines with 10,000 lux—about 100 times brighter than most indoor lighting—for 30 minutes a day, preferably right after waking up. When done at the same time every day, this kind of therapy has been shown to recalibrate your body clock and reduce levels of cortisol, a stress hormone. Learn how light therapy works and find other ways to fight the winter blues in the videos below.

Seasonal Affective Disorder Explained

Find out why fall and winter can be so depressing.

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Key Facts In This Video

  1. Season Affective Disorder is the beginning or worsening of the symptoms of depression which occurs with the changing of the seasons. 00:26

  2. Studies have found that when people are exposed to bright light early in the morning, their production of melatonin happens earlier in the evening. 01:34

  3. It's thought that this disorder is a biochemical evolutionary hangover from our mammalian ancestors who hibernated during the winter months. 02:08

How Light Can Help SAD

Explore the possible treatments for seasonal affective disorder.

How Your Brain's Internal Clock Works

A dip in daylight can have a big effect on your biological clock.

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Seasons
Winter