Grey skies and frigid temperatures make us all want to hibernate under the covers a little longer. Gloomy days can lead to a seasonal funk that we simply try to power through. For most of us, a funny movie and a cup of tea are enough to lift our spirits. For many, though, the “winter blues” aren’t simple. According to the American Psychiatric Association,  the short, dark days can lead to a syndrome called Seasonal Affective Disorder (SAD), a type of depression that starts and ends at roughly the same time every year, usually in winter—though on rare occasions it can occur in summer as well.

According to Mental Health America, about 5% of people in the US experience seasonal depression, and four out of five of those affected are women. Normally, people begin to experience symptoms in their 20s, though it can start earlier. Typical symptoms for SAD include feeling sad, difficulty waking up on schedule, daytime fatigue, weight gain, and carbohydrate cravings. Once the SAD takes hold, symptoms can include non-seasonal issues like lack of enthusiasm for work or other activities, reduced social contact, and anxiety.

Typically, winter SAD is triggered by decreasing light as the days get shorter.  Spending more time indoors, without access to real sunlight, makes matters worse. The symptoms can begin in late fall, with January and February being the worst months overall. Many people see the symptoms begin to dissipate as spring approaches and days get longer. While the cause of SAD remains a mystery, research has linked SAD to a biochemical imbalance brought on by the lack of sunlight during short winter days. According to the National Institute of Mental Health, the regulation of serotonin, which helps control mood, doesn’t function properly owing to the lack of full-spectrum light. In other studies, people with SAD produce too much melatonin, which is central to our sleep-wake cycle. Too much melatonin means increased fatigue.

Treatments include light therapy, antidepressants, vitamin D, and talk therapy.  Light therapy uses a very bright lightbox (10,000 lux) for 30-45 minutes a day, usually in the morning. (Some people use plant lights, with are weaker but easier to find.) This therapy has been shown to help alleviate the lack of light outdoors. However, people with certain eye diseases or using certain medications that increase sensitivity to sunlight—such as RetinA and certain antibiotics—should get medical advice before starting treatment.

Antidepressants are often prescribed for depression disorders, but do consult with your doctor about possible side effects and risks. Many people believe increasing vitamin D will help against SAD, but findings as to its efficacy are mixed.

Cognitive behavioral therapy (CBT) is a type of talk therapy that has been shown to produce the longest-lasting effects of any treatment, according to The National Institute of Mental Health. CBT programs lasting 6 weeks (two sessions per week) focus on replacing negative thoughts with more positive ones. The approach has been adapted for people with SAD.

SAD can affect anyone. Self-care is important.  Eat a healthy diet. Get enough (but not too much) sleep. Keep active. Educate yourself and if you are experiencing symptoms, call your doctor.