Department of Psychiatry
Penn Behavioral Health

PAH Outpatient Behavioral Health Clinic

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Newsletter: December 2009

Seasonal Affective Disorder (SAD)

Cristina Laurita, MA


Do the cold and cloudy days of winter get you down?  Over fifteen million people in the US experience symptoms of depression during the winter months, which may be a sign of Seasonal Affective Disorder (SAD).  SAD is a mood disorder that is a form of depression and is speculated to be linked to seasonal variations in the amount of sunlight to which people are exposed.  Symptoms of SAD typically occur somewhere between September and April—most strongly during December, January, and February—and subside during the spring and summer months.  SAD can be much more than the winter blahs or cabin fever.  The depressive symptoms of SAD can be strong enough to have a negative impact on a person’s work, school, health, and relationships.  As with anything, there are degrees or levels of severity to SAD.  While for some people it can progress to a major depressive episode, for others it can resolve itself on its own when the seasons change. 

SAD is generally diagnosed if a person has experienced at least two seasonal episodes of depression in consecutive years and their symptoms disappear during the spring and summer months.  It is important to distinguish between a pattern of depressive symptoms caused by the change in seasons and a pattern of depressive symptoms that might have other causes (e.g., becoming depressed every winter because a death of a loved one occurred during a past winter and you are reminded of that loss each subsequent winter). 

Some of the common symptoms of SAD include:

  • depressive symptoms that begin during the fall or winter months
  • feeling sluggish or tired during the day
  • lack of energy
  • diminished interest in things you used to enjoy
  • withdrawing from social activities and/or relationships
  • changes in appetite and weight (e.g., carbohydrate cravings, weight gain)
  • sleeping more

Although the exact causes of SAD are unknown, there are a number of hypotheses about what leads to SAD.  The reduction in levels of sunlight during the fall and winter months can disturb circadian rhythm (the body’s sleep/wake cycle), and this alteration may cause depression.  Melatonin, a sleep-related hormone that contributes to symptoms of depression, is produced at increased levels when the days are shorter and darker.  Some research also suggests that a reduction in exposure to sunlight can lead to a decrease in the body’s production of serotonin (the brain chemical that impacts mood), which can contribute to depression.  Due to the connection between SAD and levels of exposure to sunshine, people who live in northern regions and areas that get fewer days of sunshine during the winter months are more likely to experiences symptoms of SAD. 

How to combat the winter blues?  There are a number of treatment possibilities.  One of the most logical, though not always possible, is to increase one’s exposure to sunlight, such as by spending more time outdoors or by sitting near a window.  Since there are usually fewer sunny days during the fall and winter months, an increasingly common treatment for sufferers of SAD is light box therapy (also referred to as bright light therapy or phototherapy).  This involves sitting near a special lamp that mimics natural outdoor light for a set period of time each day (usually about thirty minutes each morning).  Exposure to this light can create a biochemical change in the brain and lift one’s mood, such as by regulating the body’s circadian rhythms and suppressing the release of melatonin.  It is important to check with your doctor and mental health professional before trying light therapy, in order to be sure that it is an appropriate and safe treatment for you.  For instance, some studies suggest that light therapy can trigger episodes of mania in people who suffer from bipolar disorder.  Other ways to fight the symptoms of SAD are to exercise regularly, maintain a healthy diet, keep a regular and adequate sleep schedule, and to socialize, especially by maintaining good relationships with friends, family, and loved ones.  Antidepressant medications are sometimes used to treat more severe cases of SAD.  Psychotherapy is often a good choice in the treatment of SAD and can help you work through the symptoms and feel better.  Research also suggests that light therapy is more effective when combined with psychotherapy.