Seasonal Affective Disorder: Causes and Risks

The blues that often come with winter weather are nothing unusual. It's natural to feel a little low when the sky is overcast and weather conditions make outside activities difficult. However, sometimes you can start to feel so low that it can be hard to get out of bed or can be difficult to enjoy activities that you once loved. If seasonal changes dramatically impact your life, you might be suffering from seasonal affective disorder, or SAD.
 
Researchers are currently working to understand the causes and risk factors for SAD. Up to this point, doctors and scientists have produced several working theories on why seasonal affective disorder occurs.

Seasonal Affective Disorder Explained

Seasonal affective disorder is cyclical. Therefore, its symptoms come and go as the seasons change. In general, SAD sufferers will feel symptoms in the late fall or early winter and will then see symptoms gradually disappear during the warm, more sunlight-filled spring and summer months.

However, some people with SAD will feel symptoms start in the spring and summer and then in the fall and winter months.

SAD symptoms that occur during the winter and fall months generally include:

  • Anxiety
  • Appetite changes
  • Depression
  • Difficulty concentrating
  • Hopelessness
  • Loss of energy
  • Loss of interest in normally enjoyed activities
  • Oversleeping
  • Social withdrawal
  • Weight gain.
SAD symptoms that start in the summer or spring can be quite different and might include mania, increased sexual activity and weight loss.

Causes of SAD

Winter-onset seasonal affective disorder seems to be caused by the reduction in sunlight that comes with shorter winter days. People who have SAD suffer from interferences in their natural body rhythms, from appetite to sleep cycles. This means that their internal clocks become irregular.

Some researchers think this disruption is caused when the body produces too much of the hormone melatonin, a hormone associated with sleep that is secreted in response to darkness. In general, the body produces more melatonin during the longer winter nights.

Recent studies show that some SAD sufferers have benefited from taking melatonin supplements. If this is true, then the theory that an excess of melatonin causes SAD could be incorrect.

Other scientists blame SAD on a deficiency in the chemical serotonin, which helps regulate mood. When a person is exposed to less sunlight, his brain produces less serotonin.

In a relatively new theory, some researchers speculate that people with SAD have eye problems that prevent them from adjusting to dim winter days. These people's eyes might be under-sensitive to light. This theory, however, needs more study to prove or disprove its credibility.

Risk Factors for SAD

Researchers are still investigating the risk factors for seasonal affective disorder. Some studies seem to indicate that genetics play a part in SAD, but this isn't a certainty.

Sometimes, people who suffer from certain medical conditions appear to be at a higher risk of developing SAD. These medical conditions include:

  • anxiety disorders
  • attention deficit hyperactivity disorder
  • bulimia
  • chronic fatigue syndrome
  • panic attacks.

These medical conditions could contribute to SAD due to the fact that they often interfere with serotonin production and reception in the brain.

Another risk factor for SAD is living in more northern locations, where winter days are shorter and winter nights are longer.

Also, gender seems to play a part in the likelihood that a person will develop SAD. More women have SAD than men, but men who are diagnosed with the condition often experience more severe symptoms. Age also seems to play a role, as SAD is relatively unusual in people under the age of 20.

Resources

HealthScout Network Staff. (2001). Seasonal affective fisorder. Retrieved December 9, 2007, from the HealthScout Network website: http://www.healthscout.com/ency/1/228/main.html#CausesandRiskFactorsofSeasonalAffectiveDisorder

Lurie, S.J., Gawinski, B. Peirce and Rousseau, S. (2006). Seasonal affective disorder. Retrieved December 9, 2007, from the American Academy of Family Physicians website: http://www.aafp.org/afp/20061101/1521.html

Mayo Clinic Staff. (2007). Seasonal affective disorder (SAD). Retrieved December 9, 2007, from the Mayo Clinic website: http://www.mayoclinic.com/health/seasonal-affective-disorder/DS0019