Less daylight, colder temperatures, holiday stress and post-holiday letdown — winter can be a tough season for many reasons.

For some among us, it’s worse than others. According to the Mayo Clinic, more than 3 million Americans suffer from Seasonal Affective Disorder every year. Fatigue, depression, hopelessness and social withdrawal come with the territory.

While it’s not unusual to feel some form of the so-called “winter blues,” SAD takes those feelings to another level.

According to the National Institute of Mental Health, some symptoms of SAD include:

• Having low energy
• Hypersomnia
• Overeating
• Weight gain
• Craving for carbohydrates
• Social withdrawal (feel like “hibernating”)

Risk factors include:

• Being female. SAD is diagnosed four times more often in women than men.
• Living far from the equator. SAD is more frequent in people who live far north or south of the equator.
• Family history. People with a family history of other types of depression are more likely to develop SAD than people who do not have a family history of depression.
• Having depression or bipolar disorder. The symptoms of depression may worsen with the seasons if you have one of these conditions (but SAD is diagnosed only if seasonal depressions are the most common).
• Younger Age. Younger adults have a higher risk of SAD than older adults. SAD has been reported even in children and teens.

According to NIMH, there are four major types treatments available to help fight the effects of SAD, including medication, light therapy, psychotherapy and taking vitamin D.

While the winter blues may hit especially hard this time of year, with financial struggles and failed new years resolutions, it never hurts to know about conditions like SAD. The more you know, the better you can face your struggles.