Seasonal affective disorder makes winter a sad season for many

depression photo

Seasonal Affective Disorder (SAD) is known by many as the “winter blues.” In reality, it’s a type of major depressive disorder that recurs during the same season each year. The most common seasonal pattern starts in the fall or winter and ends in the spring. Less commonly, a person may experience symptoms beginning in late spring or early summer.

SAD isn’t a separate depressive disorder. To be diagnosed with SAD, you must meet the criteria for major depression that coincides with specific seasons for at least two years. You must also have seasonal depressions much more frequently than any non-seasonal ones.

SAD affects about 10 million Americans, with an additional 10 to 20 percent possibly having a mild form. Women are four times more likely to experience SAD than men. The usual age of onset is between 18 and 30 years. Some people’s symptoms are severe enough to impact their quality of life and six percent require hospitalization.


While the specific cause for SAD is unknown, there are some factors that may play a role:

  • Your biological clock (circadian rhythm): the decrease in sunlight in the fall and winter may cause winter-onset SAD by disrupting your body’s internal clock and leading to feelings of depression;
  • Serotonin levels: a decrease in serotonin (a brain chemical that affects mood) may contribute to SAD. Reduced sunlight can cause a drop in serotonin, triggering depression; and
  • Melatonin levels: seasonal changes can disrupt your body’s melatonin levels, which plays a role in sleep patterns and mood.

SAD symptoms

Most of the time, SAD symptoms appear during late fall or early winter and go away during spring and summer. Less commonly, people have the opposite pattern. Either way, symptoms may start out mild then become more severe as the season progresses.

Symptoms may include:

  • Feeling depressed most of the day, nearly every day;
  • Losing interest in activities you once enjoyed;
  • Having low energy;
  • Having problems with sleeping;
  • Experiencing changes in your appetite or weight;
  • Feeling sluggish or agitated;
  • Having difficulty concentrating;
  • Feeling hopeless, worthless, or guilty; and
  • Having frequent thoughts of death or suicide.

Symptoms specific to winter-onset SAD may include:

  • Oversleeping;
  • Appetite changes, especially a craving for foods high in carbohydrates;
  • Weight gain; and
  • Tiredness or low energy.

Symptoms specific to summer-onset SAD may include:

  • Trouble sleeping (insomnia);
  • Poor appetite;
  • Weight loss; and
  • Agitation or anxiety.

For certain people with bipolar disorder, seasonal changes can particularly affect them. Spring and summer can cause symptoms of mania or a less intense form (hypomania), and fall and winter can produce depression.

Unfortunately, there are several factors that can increase your risk for SAD:

  • Being female;
  • Living far from the equator: SAD is more frequent in people who live far north or south of the equator;
  • Family history: if you have a family history of other depression types, you have a higher risk;
  • Having depression or bipolar disorder: your symptoms of depression may worsen with the seasons if you have one of these conditions, but SAD is only diagnosed if seasonal depressions are the most common; and
  • Younger age.

Treatment & management

There are ways to manage your SAD. Since decreased sun exposure is partially what causes SAD and increasing your exposure can lessen your symptoms, try to experience as much daylight as possible. Eat healthily and stay active. Research shows exercise and planning enjoyable activities can be effective ways to decrease the impact of SAD. Spend time with family and friends to lift your spirits and avoid social isolation. If you’re still struggling, seek professional help.

Treatment for SAD consists of four types that may be used alone or in combination.

Medications used to treat SAD include:

  • Selective Serotonin Reuptake Inhibitors (SSRIs): Celexa, Lexapro, Prozac, Fluvoxamine, Paxil, Zoloft, Trintellix; and
  • Antidepressants: Aplenzin, Wellbutrin XL.

Light therapy has been a SAD treatment mainstay since the 1980s, with the idea being to replace the diminished fall and winter sunshine with bright, artificial light. Patients’ symptoms are relieved by sitting in front of a light box first thing in the morning, every day from early fall until spring.

Psychotherapy involves the use of an adapted form of Cognitive Behavioral Therapy (CBT), called CBT-SAD. This therapy uses the basic CBT techniques of replacing negative thoughts with positive ones, as well as incorporating a technique called behavioral activation. During behavioral activation, the person identifies engaging and pleasurable activities to improve coping with winter.

Currently, vitamin D supplementation is not considered effective by itself. The reason for its use is because people with SAD have low vitamin D levels, which are usually due to insufficient dietary intake or sunshine exposure. The evidence for supplementation has been mixed, though, with some studies suggesting it to be extremely effective and others not effective at all.

About the Author

Julie Kaplan, Pharm. D.
Julie Kaplan is a licensed pharmacist in Virginia and the District of Columbia. She received a Bachelor’s of Arts in English from The College of William and Mary and a Doctor of Pharmacy from Virginia Commonwealth University. She has experience in patient communication from working as a retail pharmacist.