Seasonal Affective Disorder (SAD)

Browse By All Topics


Seasonal Affective Disorder (SAD)

Topic Overview

What is seasonal affective disorder (SAD)?

Seasonal affective disorder, or SAD, is a type of depression that affects a person during the same season each year. If you get depressed in the winter but feel much better in spring and summer, you may have SAD.

Anyone can get SAD, but it is more common in:

  • People who live in areas where winter days are very short or there are big changes in the amount of daylight in different seasons.
  • Women.
  • People between the ages of 15 and 55. The risk of getting SAD for the first time goes down as you age.
  • People who have a close relative with SAD.

What causes SAD?

Experts are not sure what causes SAD, but they think it may be caused by a lack of sunlight. Lack of light may upset your sleep-wake cycle and other circadian rhythms. And it may cause problems with a brain chemical called serotonin that affects mood.

What are the symptoms?

If you have SAD, you may:

  • Feel sad, grumpy, moody, or anxious.
  • Lose interest in your usual activities.
  • Eat more and crave carbohydrates, such as bread and pasta.
  • Gain weight.
  • Sleep more and feel drowsy during the daytime.

Symptoms come and go at about the same time each year. For most people with SAD, symptoms start in September or October and end in April or May.

How is SAD diagnosed?

It can sometimes be hard to tell the difference between nonseasonal depression and SAD, because many of the symptoms are the same. To diagnose SAD, your doctor will want to know if:

  • You have been depressed during the same season and have gotten better when the seasons changed for at least 2 years in a row.
  • You have symptoms that often occur with SAD, such as being very hungry (especially craving carbohydrates), gaining weight, and sleeping more than usual.
  • A close relative—a parent, brother, or sister—has had SAD.

How is it treated?

Doctors often prescribe light therapy to treat SAD. There are two types of light therapy:

  • Bright light treatment. For this treatment, you sit in front of a "light box" for half an hour or longer, usually in the morning.
  • Dawn simulation. For this treatment, a dim light goes on in the morning while you sleep, and it gets brighter over time, like a sunrise.

Light therapy works well for most people who have SAD, and it is easy to use. You may start to feel better within a week or so after you start light therapy. But you need to stay with it and use it every day until the season changes. If you don't, your depression could come back.

Other treatments that may help include:

  • Antidepressants. These medicines can improve the balance of brain chemicals that affect mood.
  • Counseling. Some types of counseling, such as cognitive-behavioral therapy, can help you learn more about SAD and how to manage your symptoms.

If your doctor prescribes antidepressants, be sure you take them the way you are told to. Do not stop taking them just because you feel better. This could cause side effects or make your depression worse. When you are ready to stop, your doctor can help you slowly reduce the dose to prevent problems.

You may feel better if you get regular exercise. Being active during the daytime, especially first thing in the morning, may help you have more energy and feel less depressed. Moderate exercise such as walking, riding a stationary bike, or swimming is a good way to get started.

Frequently Asked Questions

Learning about seasonal affective disorder (SAD):

Being diagnosed:

Getting treatment:

Living with SAD:

Health Tools Health Tools help you make wise health decisions or take action to improve your health.

Health Tools help you make wise health decisions or take action to improve your health.

Actionsets help people take an active role in managing a health condition.Actionsets are designed to help people take an active role in managing a health condition.
 Depression: Dealing With Medicine Side Effects
 Depression: Helping Someone Get Treatment
 Depression: Supporting Someone Who Is Depressed
 Depression: Taking Antidepressants Safely
 Seasonal Affective Disorder: Using Light Therapy


If you have seasonal affective disorder (SAD), you will usually have symptoms of depression during the winter when there is less daylight (October through April). Symptoms of SAD include:

  • Difficulty concentrating.
  • Low energy and fatigue.
  • Reduced interest in daily activities, especially social activities.
  • Moodiness (depressed, sad, or unusually quiet).
  • Increased appetite.
  • Cravings for complex carbohydrates (such as pasta and bread).
  • Weight gain.
  • Increased sleep.
  • Loss of interest in sex.
  • Irritability.

Exams and Tests

Before diagnosing you with seasonal affective disorder (SAD), a doctor will ask about your medical history.

Your doctor may order blood tests to check for other conditions, such as hypothyroidism, that could be causing your depression. He or she also may ask you to complete a questionnaire regarding changes in your sleep patterns, social activity, mood, weight, appetite, and energy levels.

The questionnaire may ask the following:

  • Do you feel a dramatic reduction in energy when the days get shorter?
  • Do you have difficulty waking up in the morning?
  • Do you sleep more than you used to or sleep too much?
  • Are you eating more than you used to or more than you should?
  • Have you gained weight?

Your doctor may also do a mental health assessment, which includes an evaluation of your emotional functioning and your ability to think, reason, and remember (cognitive functioning). The assessment may also include written or verbal tests and lab tests (such as blood and urine tests). During the interview, your doctor will assess your appearance, mood, behavior, thinking, reasoning, memory, and ability to express yourself and may ask about your personal relationships and family history of SAD.

Treatment Overview

Treatment for seasonal affective disorder (SAD) doesn't cure the seasonal depression, but it can help relieve your symptoms. Your symptoms may improve if you get more natural sunlight during the daytime. Light therapy is the main treatment for SAD, and research is continuing to determine the most effective way to use it. Medicines and counseling may also be used to treat SAD.

Light therapy

There are two types of light therapy. One type is bright light treatment, in which you sit in front of a "light box" for a certain amount of time (usually in the morning). The other type is dawn simulation, which is done while you sleep. For dawn simulation, a low-intensity light is timed to go on at a certain time in the morning before you wake up, and it gradually gets brighter.

Light boxes use fluorescent lights that are brighter than indoor lights but not as bright as sunlight. Ultraviolet light, full-spectrum light, tanning lamps, and heat lamps should not be used. You place the light box at a specified distance from you on a desk or in front of a chair and use it while you read, eat breakfast, or work at a computer. Light therapy is usually prescribed for 30 minutes to 2 hours, depending on the intensity of the light used and on whether you are starting out or are using it to maintain a response.

It may take as little as 3 to 5 days or up to 2 weeks before you respond to light therapy. Stopping light therapy might cause you to relapse back into depression.

Light therapy may work by resetting your "biological clock" (circadian rhythms), which controls sleeping and waking.

If you have eye problems or you take medicines that make you light-sensitive, ask your doctor about whether light therapy is safe for you. Before you start treatment, tell your doctor about any other conditions you have and about the medicines you are taking.

Click here to view an Actionset.Seasonal Affective Disorder: Using Light Therapy


Antidepressants effectively treat episodes of depression in people who have seasonal affective disorder. You may start to feel better within 1 to 3 weeks of taking antidepressant medicine. But it can take as many as 6 to 8 weeks to see more improvement. If you have questions or concerns about your medicines, or if you do not notice any improvement by 3 weeks, talk to your doctor. Antidepressants can be used along with light therapy or alone. The most common antidepressants used to treat people with seasonal affective disorder include:

SSRIs are usually the first type of antidepressants given to treat SAD. SSRIs often have less serious side effects than other antidepressants. All antidepressant medicines are started at low doses and increased gradually. When stopped, they should be decreased gradually to avoid side effects.

General side effects of antidepressant medicines can include:

  • Nausea, loss of appetite, or diarrhea.
  • Anxiety or nervousness.
  • Difficulty sleeping or drowsiness.
  • Loss of sexual desire or ability.
  • Headaches.

Bupropion can cause dry mouth. Bupropion should not be taken if you have seizures, severe problems with eating, or an eating disorder, because it can cause seizures.

Click here to view an Actionset.Depression: Dealing With Medicine Side Effects
Click here to view an Actionset.Depression: Taking Antidepressants Safely


Counseling, such as interpersonal therapy and cognitive-behavioral therapy, may help with your treatment for SAD. You may choose individual counseling, participate in group counseling, or seek family therapy. During counseling, you will learn about SAD, ways to handle the symptoms, and how to help prevent future depressive episodes. If you have had SAD for a long time, your family members may also benefit from counseling.

Home Treatment

Home treatment is very important in the treatment of seasonal affective disorder (SAD). Home treatment for an episode of depression may include a combination of the following:

Physical activity

Being physically active during the daytime, especially first thing in the morning during winter, may help improve your energy level and relieve depression. Moderate exercises like walking, stationary cycling, and swimming are a good way to start an exercise routine.

Experts say to do either of these things to get and stay healthy:1

  • Moderate activity for at least 2½ hours a week. One way to do this is to be active 30 minutes a day, at least 5 days a week. Moderate activity means things like brisk walking, brisk cycling, or shooting baskets. But any activities—including daily chores—that raise your heart rate can be included. You notice your heart beating faster with this kind of activity.
  • Vigorous activity for at least 1¼ hours a week. One way to do this is to be active 25 minutes a day, at least 3 days a week. Vigorous activity means things like jogging, cycling fast, or cross-country skiing. You breathe rapidly and your heart beats much faster with this kind of activity.

It's fine to be active in blocks of 10 minutes or more throughout your day and week. You can choose to do one or both types of activity.

Moderate activity is safe for most people, but it's always a good idea to talk to your doctor before you start an exercise program.

Also try to do exercises to strengthen muscles at least 2 times each week. Examples include weight training or stair climbing on 2 or more days that are not in a row. For best results, use a resistance (weight) that gives you muscle fatigue after 8 to 12 repetitions of each exercise.

Healthy diet

Eating a healthy, balanced diet is helpful for any type of depression and may help relieve some of the symptoms of SAD.

Complementary treatment

The following complementary treatments may be helpful in treating symptoms of SAD, although there currently is not enough scientific evidence to prove their usefulness.

  • An herb called St. John's wort may help ease depression symptoms.
  • Melatonin is a hormone that may help regulate your biological clock (circadian rhythms). But you need to take a very low dose at a specific time of the day.

Be sure to check with your doctor before you try these complementary therapies, because they may interact with other medicines you are taking.

You should not take St. John's wort if you are taking other antidepressants. Also, St. John's wort may cause light sensitivity. If you are using light therapy, you may want to discuss with your doctor whether St. John's wort is right for you in the treatment of SAD.

Research on the effectiveness of other SAD treatments is ongoing.

Advice for caregivers

Sometimes family members and friends are not sure how to help someone who has seasonal affective disorder. It may help to:

  • Spend time with your loved one even though he or she may be withdrawn or quiet.
  • Offer to help with daily tasks that temporarily may be too difficult to do alone. But it is important that you do not enable the person to remain depressed by taking over all of his or her daily responsibilities.
  • Take a walk or do some other type of exercise activity together. Getting out first thing in the morning for a walk may be helpful.
  • Help the person to stay with the prescribed treatment plan.

For more information on helping someone with SAD or depression, see:

Click here to view an Actionset.Depression: Helping Someone Get Treatment.
Click here to view an Actionset.Depression: Supporting Someone Who Is Depressed.

Unfortunately, many people don't seek treatment for mental health problems. You may not seek treatment because you think the symptoms are not bad enough or that you can work things out on your own. But getting treatment is important.

If you need help deciding whether to see your doctor, see some reasons why people don't get help and how to overcome them.

Other Places To Get Help


Healthy Minds. Healthy Lives.American Psychiatric Association
Wilson Boulevard
Arlington, VA 22209
Phone: 1-888-35-PSYCH
Web Address:

This online resource is provided by the American Psychiatric Association for anyone seeking mental health information. It includes information on many common mental health concerns, including warning signs of mental disorders, treatment options, and preventive measures.

KidsHealth for Parents, Children, and Teens
Nemours Home Office
10140 Centurion Parkway
Jacksonville, FL 32256
Phone: (904) 697-4100
Web Address:

This website is sponsored by the Nemours Foundation. It has a wide range of information about children's health—from allergies and diseases to normal growth and development (birth to adolescence). This website offers separate areas for kids, teens, and parents, each providing age-appropriate information that the child or parent can understand. You can sign up to get weekly emails about your area of interest.

Mental Health America
2000 North Beauregard Street, 6th Floor
Alexandria, VA 22311
Phone: 1-800-969-NMHA (1-800-969-6642) referral service for help with depression
(703) 684-7722
Fax: (703) 684-5968
Web Address:

Mental Health America (formerly known as the National Mental Health Association) is a nonprofit agency devoted to helping people of all ages live mentally healthier lives. Its website has information about mental health conditions. It also addresses issues such as grief, stress, bullying, and more. It includes a confidential depression screening test for anyone who would like to take it. The short test may help you decide whether your symptoms are related to depression.

National Alliance on Mental Illness (NAMI)
3803 North Fairfax Drive
Suite 100
Arlington, VA  22203
Phone: 1-800-950-NAMI (1-800-950-6264) hotline for help with depression
(703) 524-7600
Fax: (703) 524-9094
Web Address:

The National Alliance on Mental Illness is a national self-help and family advocacy organization dedicated solely to improving the lives of people who have severe mental illnesses such as schizophrenia, bipolar disorder (manic depression), major depression, obsessive-compulsive disorder, and panic disorder. NAMI focuses on support, education, advocacy, and research. The mission of the organization is to "eradicate mental illness and improve the quality of life of those affected by these diseases."



  1. U.S. Department of Health and Human Services (2008). 2008 Physical Activity Guidelines for Americans (ODPHP Publication No. U0036). Washington, DC: U.S. Government Printing Office. Available online:

Other Works Consulted

  • American Psychiatric Association (2010). Practice Guideline for the Treatment of Patients With Major Depressive Disorder, 3rd ed. Available online:
  • Byrne B, Brainard GC (2008). Seasonal affective disorder and light therapy. Sleep Medicine Clinics, 3: 307–315.
  • Melatonin (2009). Review of Natural Products. St. Louis: Wolters Kluwer Health.
  • Provencio I (2009). Chronobiology. In BJ Sadock et al., eds., Kaplan and Sadock’s Comprehensive Textbook of Psychiatry, 9th ed., vol. 1, pp. 198–210. Philadelphia: Lippincott Williams and Wilkins.
  • Sadock BJ, Sadock VA (2007). Mood disorders. In Kaplan and Sadock's Synopsis of Psychiatry, 10th ed., pp. 527–562. Philadelphia: Lippincott Williams and Wilkins.
  • Shirani A, St Louis EK (2009). Illuminating rationale and uses for light therapy. Journal of Clinical Sleep Medicine, 5(2): 155–163.
  • U.S. Department of Health and Human Services (2008). 2008 Physical Activity Guidelines for Americans (ODPHP Publication No. U0036). Washington, DC: U.S. Government Printing Office. Available online:
  • Westrin A, Lam RW (2007). Seasonal affective disorder: A clinical update. Annals of Clinical Psychiatry, 19(4): 239–246.


ByHealthwise Staff
Primary Medical ReviewerKathleen Romito, MD - Family Medicine
Specialist Medical ReviewerAlfred Lewy, MD, PhD - Psychiatry
Last RevisedJune 20, 2012

This information does not replace the advice of a doctor. Healthwise, Incorporated disclaims any warranty or liability for your use of this information. Your use of this information means that you agree to the Terms of Use.

How this information was developed to help you make better health decisions.

© 1995-2012 Healthwise, Incorporated. Healthwise, Healthwise for every health decision, and the Healthwise logo are trademarks of Healthwise, Incorporated.