How To Tell If You Have Seasonal Depression (Plus, How To Treat It)

Winter can be a massive mood killer. Days are shorter, temperatures are colder, and staying in your cozy, warm bed all day can feel like a welcomed escape from the frigid world outside.

Seasonal affective disorder (SAD), aka seasonal depression, occurs in areas that experience lower levels of sunlight during certain times of the year. 

In the United States, it's most prevalent in the northern regions of the country—i.e., Alaska, the Pacific Northwest, the Midwest, and the Northeast. The further north you live1 (i.e., the further you are from the equator), the more susceptible you are. 

According to a 2015 article from Depression Research and Treatment, SAD is four times more common in women than men, and cases typically begin between the ages of 18 and 30. 

People with SAD have trouble regulating the synthesis of serotonin, aka the "feel good" hormone. Many also experience an overproduction of melatonin, the hormone that causes sleepiness when it gets dark. 

The combination of decreased serotonin and increased melatonin messes with the circadian rhythm, or the body's "biological clock." This effect is most intense during the months leading up to and following the winter solstice (i.e., November, December, January, and February), which is when days are the shortest and sunlight is least available.

What's more, bundling up when we do head outside in the winter sun leaves little skin exposed for cutaneous vitamin D production. Vitamin D plays a role in the regulation of both serotonin and melatonin, making healthy D levels an important factor in whether or not SAD symptoms exist (or persist). 

Seasonal depression affects certain individuals living in northern latitudes. Even more people in these locations are impacted by the winter blues each year.