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Home > Wellness > Health Library > Seasonal Affective Disorder (SAD)
Seasonal affective disorder, or SAD, is a type of
depression that occurs during the same
season each year. You may have SAD if you felt depressed during the last two winters but felt much better in
spring and summer.
Anyone can get SAD, but it's more common in:
SAD is sometimes called winter depression or seasonal depression.
Experts aren't sure what causes
SAD. But they think it may be caused by a lack of sunlight. Lack of light may:
If you have SAD, you
Symptoms come and go at about the same time each year.
Most people with SAD start to have symptoms in September or October and feel better by
April or May.
It can sometimes be hard to
tell the difference between SAD and other types of depression because many of the
symptoms are the same. To diagnose SAD, your doctor will ask
You may need to have blood tests to rule out other conditions that can cause similar symptoms, such as low thyroid (hypothyroidism).
Your doctor may also do a mental health assessment to get a better idea of how you feel and how well you are able to think, reason, and remember.
Light therapy is the main treatment for SAD. Medicines and counseling may also help.
Experts think light therapy works by resetting your biological clock. It helps most people who have SAD, and it's easy to use.
There are two types of light therapy:
Light boxes use fluorescent lights that are brighter than indoor lights but not as bright as sunlight. Ultraviolet lights, full-spectrum lights, tanning lamps, and heat lamps should not be used.
Light therapy is usually prescribed for 30 minutes to 2 hours a day. The amount of time depends on how strong the light is and on whether you are starting out or are have been using it for a while.
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.
Antidepressant medicines may help people who have SAD. They may be used alone or with light therapy. The most common ones prescribed for SAD include:
If your doctor prescribes an antidepressant, be sure you
take it the way you're told to. Do not stop taking it suddenly. 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
Counseling may also help. Some
types of counseling, such as
cognitive-behavioral therapy and interpersonal therapy, can help you learn more
about SAD, how to manage your symptoms, and how to help prevent future episodes..
Regular exercise is one of the best things you can do for yourself.
Getting more sunlight may help too, so try to get outside to exercise when the sun is shining. Being active during the daytime, especially early in the day, may
help you have more energy and feel less depressed.
Moderate exercise is safe for most people. But it's always a good idea to talk to your doctor before you start an exercise program.
Some people try complementary treatments to help with SAD. One example is melatonin, a hormone that may help regulate your biological clock. If you want to use melatonin or other complementary treatments, be sure to check with your doctor first. These medicines may interact with other treatments.
Health Tools help you make wise health decisions or take action to improve your health.
Learning about seasonal affective disorder (SAD):
Living with SAD:
Other Works Consulted
American Psychiatric Association (2010). Practice Guideline for the Treatment of Patients With Major Depressive Disorder, 3rd ed. Available online: http://psychiatryonline.org/guidelines.aspx.
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: http://www.health.gov/paguidelines/guidelines/default.aspx.
Westrin A, Lam RW (2007). Seasonal affective disorder: A clinical update. Annals of Clinical Psychiatry, 19(4): 239–246.
ByHealthwise StaffPrimary Medical ReviewerKathleen Romito, MD - Family MedicineSpecialist Medical ReviewerAlfred Lewy, MD, PhD - Psychiatry
Current as ofApril 21, 2015
Current as of:
April 21, 2015
Kathleen Romito, MD - Family Medicine & Alfred Lewy, MD, PhD - Psychiatry
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