We are drawing closer and closer to that time of year in the northern hemisphere. Soon, days will get shorter, the sun will set earlier…in fact, the sun will actually appear less in general as gloomy, cooler weather days start to outnumber the bright and warm ones. For an estimated 5% of Americans, this will trigger Seasonal Affective Disorder or what’s better known as Winter Blues. And while it might seem like a convenient case of the placebo effect to say gloomy weather is what brings a person down, the truth is that Seasonal Affective Disorder (SAD) is a legitimate form of depression brought on by the reduced daylight hours of winter months.

So, should you actually take this seriously?

Absolutely.

“The way we diagnose SAD is to diagnose depression that follows a seasonal pattern,” says Kelly Rohan, Ph.D., professor of psychological science at the University of Vermont, Burlington. "Many of the symptoms of SAD are the same as those of clinical, or major, depression—low mood, loss of interest in enjoyable activities, fatigue."

That sounds like standard depression, doesn’t it?

Well, actually, people with Seasonal Affective Disorder are found to sleep more and eat more as a result of their depression —  contrasting symptoms of major depression in which people tend to lose their appetite as well as have troubles getting good sleep. The tangible result of the Winter Blues then becomes weight gain for many. Research suggests the people at the highest risk of having SAD during the fall and winter months are women, people in their early 20s, people with a family history of SAD, and those who also have major depression or bipolar disorder, and unsurprisingly, people who live closer to the north or south poles where the days are already exceptionally short during winter months, to begin with.

There are many different pieces of the puzzle that explain how SAD starts to take place. Experts believe it’s the result of the body’s struggle to adjust to when it should produce melatonin, the hormone that signals when it’s time to wind down for a full night of sleep. Early evenings trigger the body to make melatonin earlier and delayed sunrises allows us to feel groggy and slow through more of the morning. At the same time, our body starts to experience dips in serotonin, the neurotransmitter that regulates our mood.

Technically, we all are affected by the changing seasons and feeling some level of the winter blues is actually very common. But a little fatigue and feeling slightly down don’t necessarily mean you’re going to lose the ability to enjoy other aspects of life. When those winter blues start permeating all aspects of life, well beyond the urge to bundle up and stay inside all day, you may be struggling with legitimate Seasonal Affective Disorder.

So no, the winter blues aren’t a myth. For some, it is a very real disorder worth taking seriously. Getting sunlight whenever possible and of course, staying active are two of the most common approaches to battling this peculiar disorder.