Seasonal Affective Disorder
Seasonal affective disorder (SAD) is a type of depression
The cause of SAD is not completely understood. It is clearly related to changes in seasonal light. Light affects cycles in the body. Lack of light during the winter months could possibly throw off levels of hormones and brain chemicals. This could contribute to the symptoms of SAD.
Scientists are also researching if SAD is related to lack of the chemical serotonin in the brain.
A risk factor is something that increases your chance of getting a disease or condition.
- Sex: female
- Living in northern latitudes
People with SAD have seasonal symptoms that come and go each year. They usually peak during the winter and disappear during the spring and summer.
Symptoms can include:
- Depressed mood, feelings of sadness
- Cravings for sweet or starchy foods
- Significant weight gain or loss
- Lack of energy
- Oversleeping or insomnia
- Social withdrawal
- Difficulty concentrating
- Decreased sexual desire
The doctor will ask about your symptoms and medical history, and perform a physical exam. You may be referred to a specialist in treating depression.
A diagnosis of SAD will only be made if you have some of the symptoms above and:
- Your symptoms have occurred annually for at least two years
- You have complete relief from symptoms during the summer months
Light therapy is simple. The light box is made up of fluorescent bulbs, a reflective surface, and a diffusing screen. Ordinary household lighting is not sufficient. You sit a few feet away from the ultra-bright light for a certain amount of time each day, usually in the morning. You will be able to read or work during the therapy, as your eyes will remain open. Your doctor will probably start you off with 15-20 minutes a day. You will gradually increase the time, usually to 30-45 minutes daily.
There is some evidence that light therapy may be as effective as antidepressant therapy, but with fewer side effects. *
Tanning beds are not recommended as a source of light therapy. They give off ultraviolet light, which can increase the risk of cancer. They also have not been proven effective for treating SAD. Many people find that getting outdoors for a walk each day is also helpful.
Your doctor may prescribe anti-depressant medications. These medications are usually prescribed when a person does not feel better with light therapy or if the depression is very severe.
A medication called
Therapists can help you learn ways of managing stress and the symptoms of SAD.
Depression and Bipolar Support Alliance (DBSA)
National Mental Health Association
Canadian Mental Health Center
Canadian Psychological Association
American Academy of Family Physicians website. Available at: http://www.aafp.org/online/en/home.html .
Johansson C, Smedh C, Partonen T, et al. Seasonal affective disorder and serotonin-related polymorphisms. Neurobiology of Disease. 2001;8:351–357.
National Mental Health Association website. Available at: http://www.nmha.org/ .
Seasonal affective disorder. Mayo Clinic website. Available at: http://www.mayoclinic.com/health/seasonal-affective-disorder . Updated July 2008. Accessed February 23, 2009.
Society for Light Treatment and Biological Rhythms website. Available at: http://www.websciences.org/sltbr/ .
*7/20/06 DynaMed's Systematic Literature Surveillance http://www.epnet.com/dynamed/what.php : Lam RW, Levitt AJ, Levitan RD, et al. The Can-SAD study: a randomized controlled trial of the effectiveness of light therapy and fluoxetine in patients with winter seasonal affective disorder. Am J Psychiatry . 2006;163:805-812.
Last reviewed January 2009 by
Please be aware that this information is provided to supplement the care provided by your physician. It is neither intended nor implied to be a substitute for professional medical advice. CALL YOUR HEALTHCARE PROVIDER IMMEDIATELY IF YOU THINK YOU MAY HAVE A MEDICAL EMERGENCY. Always seek the advice of your physician or other qualified health provider prior to starting any new treatment or with any questions you may have regarding a medical condition.
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