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Seasonal Affective Disorder

Woman checking her phone on a cold winter night.

What is seasonal affective disorder?

Seasonal affective disorder, or SAD, is type of depression. It happens during certain seasons of the year—most often fall or winter. It is thought that shorter days and less daylight may trigger a chemical change in the brain leading to symptoms of depression. Light therapy and antidepressants can help treat SAD.

Five Facts About Depression

  • Depression is different from feeling sad or unhappy. It is not a sign of personal weakness or a condition that can be willed or wished away.

  • Get help. If you think you may be depressed, see a healthcare provider as soon as possible.

  • Women are affected more often than men.

  • Without treatment, depression can last weeks, months or years, but most people respond well to medication, therapy or a combination of the two.

  • Most people with clinical depression who seek treatment see improvement, usually within weeks.

Who is at risk for SAD?

SAD usually starts during adulthood. The risk of SAD increases with age. It’s rare in people under age 20. Women are affected more often than men.

What causes SAD?

Less sunlight and shorter days are thought to be linked to a chemical change in the brain and may be part of the cause of SAD.

Melatonin, a sleep-related hormone, also has been linked to SAD. The body naturally makes more melatonin when it’s dark. So, when the days are shorter and darker, more melatonin is made.

What are the symptoms of SAD?

There are two types of SAD:

  1. Fall-onset. This is also called "winter depression." Symptoms of depression begin in the late fall to early winter months and ease during the summer months.

  2. Spring-onset. This is also called "summer depression." Symptoms of depression begin in late spring to early summer. This type is much less common.

The following are the most common symptoms of SAD:

  • Increased sleep and daytime drowsiness

  • Loss of interest and pleasure in activities formerly enjoyed

  • Social withdrawal and increased sensitivity to rejection

  • Irritability and anxiety

  • Feelings of guilt and hopelessness

  • Fatigue, or low energy level

  • Decreased sex drive

  • Decreased ability to focus or concentrate

  • Trouble thinking clearly

  • Increased appetite, especially for sweets and carbohydrates

  • Weight gain

  • Physical problems, such as headaches

Symptoms tend to come back and then improve at about the same times every year.

The symptoms of SAD may look like other mental health conditions. Always see a healthcare provider for a diagnosis.

How is SAD diagnosed?

Pedestrians walking along a busy street during the winter.

Depression often happens with other conditions, such as heart disease or cancer. It may also happen with other mood disorders, such as substance abuse or anxiety. For these reasons, early diagnosis and treatment is key to recovery.

A diagnosis of SAD may be made after a careful mental health exam and medical history done by a psychiatrist or other mental health professional.

How is SAD treated?

The treatments for "winter depression" and "summer depression" often differ, and may include any, or a combination, of the following:

  • Exposure to sunlight. Spending time outside or near a window can help relieve symptoms.

  • Light therapy. If increasing sunlight is not possible, exposure to a special light for a specific amount of time each day may help.

  • Psychotherapy. Cognitive-behavioral or interpersonal therapy helps change the distorted views you may have of yourself and the environment around you. It can help you improve interpersonal relationship skills, and identifying things that cause you stress as well as how to manage them.

  • Antidepressants. These prescription medicines can help correct the chemical imbalance that may lead to SAD.

There are also things you can do for yourself to help relieve symptoms:

  • Get help. If you think you may be depressed, see a healthcare provider as soon as possible.

  • Set realistic goals in light of the depression. Don’t take on too much. Break large tasks into small ones, set priorities, and do what you can as you can.

  • Try to be with other people and confide in someone. It is usually better than being alone and secretive.

  • Do things that make you feel better. Going to a movie, gardening, or taking part in religious, social, or other activities may help. Doing something nice for someone else can also help you feel better.

  • Get regular exercise.

  • Expect your mood to get better slowly, not right away. Feeling better takes time.

  • Eat healthy, well-balanced meals.

  • Stay away from alcohol and drugs. These can make depression worse.

  • Delay big decisions until the depression has lifted. Before deciding to make a significant transition—change jobs, get married or divorced—discuss it with others who know you well and have a more objective view of your situation.

  • Remember: People rarely "snap out of" a depression. But they can feel a little better day-by-day.

  • Try to be patient and focus on the positives. This may help replace the negative thinking that is part of the depression. The negative thoughts will disappear as your depression responds to treatment.

  • Let your family and friends help you.

Key points about SAD

  • SAD is a type of depression that happens during a certain season of the year—most often fall and winter.

  • There is no clear cause of SAD. Less sunlight and shorter days are thought to be linked to a chemical change in the brain and may be part of the cause of seasonal affective disorder (SAD). Melatonin, a sleep-related hormone, also may be linked to SAD.

  • In general, nearly everyone with depression has ongoing feelings of sadness, and may feel helpless, hopeless, and irritable.

  • SAD may be diagnosed after a careful mental health exam and medical history done by a psychiatrist or other mental health professional.

  • Depression is most often treated with light therapy, therapy, and in some cases antidepressants.

Depression and Sleep: Understanding the Connection

Forlorn woman

Depression and insomnia often go hand in hand. Know the connection between the two, and learn how to recognize symptoms and get treatment for both.

Read more.




Depression: What You Need to Know as You Age

Older man

Get the help you or a loved one needs, and learn the latest expert insights on coping and preventing this mood disorder.

Read more.




Seasonal Affective Disorder: What You Should Know

Woman with seasonal depression using a light box

The bright lights of the holiday season aren’t just for decoration: They can also help regulate your mood. Learn about SAD, which affects an estimated 10 to 20 percent of the population.

Read more.

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