Seasonal affective disorder (SAD) is a form of depression that occurs in relation to the seasons, most commonly beginning in winter.

The disorder may begin in adolescence or early adulthood. Like other forms of depression, it occurs more frequently in women than in men. Most people with the "winter blahs" or "cabin fever" do not have SAD.

The cause of SAD is not known, but it is thought to be related to numerous factors, including:

• Ambient light
• Body temperature
• Hormone regulation

A rare form occurs in the summer.

• Afternoon slumps with decreased energy and concentration
• Carbohydrate cravings
• Decreased interest in work or other activities
• Depression that starts in fall or winter
• Increased appetite with weight gain
• Increased sleep and excessive daytime sleepiness
• Lack of energy
• Slow, sluggish, lethargic movement
• Social withdrawal

A visit to your health care provider will look for other causes of the symptoms and confirm the diagnosis. A psychological evaluation may be needed for more severe depression.

See also: Depression

As with other types of depression, antidepressant medications and talk therapy can be effective. Light therapy using a special lamp to mimic light from the sun may also be helpful.

Symptoms commonly get better on their own with the change of seasons.

The outcome is good with continuous treatment, although some people have the disorder throughout their lives.

Seasonal affective disorder can sometimes progress to a major depressive syndrome.

Call for an appointment with your health care provider if you experience symptoms of seasonal affective disorder.

Individuals who have had recurrent seasonal depression should speak with a mental health care professional to explore treatments.

Lurie Sj, Gawinski B, Pierce D, Rousseau SJ. Seasonal affective disorder. American Family Physician. 2006;74:1521-1524.

Agerter DC, Rasmussen NH, Sutor B. Depression. In: Rakel RE, ed. Textbook of Family Medicine. 7th ed. Philadelphia, Pa: Saunders Elsevier; 2007:chap 58.