June 7, 2005
Weather and Mood
Dr. Amy Mouvius, MD
It has been a very dreary spring and gloomy weather can lead to gloomy moods. In the most extreme cases, this results in seasonal affective disorder. Seasonal affective disorder describes a condition of depression that occurs when there is less daylight.
Seasonal affective disorder (SAD) has been recognized since the 1800's though not officially named until the 1980's. The most common form is called "winter depression" and symptoms usually start in the fall and extend through the winter, with January and February being the worst months. It occurs in up to 6% of people in the US and is more prevalent at high northern latitudes. It is more common in women than men, but usually does not start until after age 20 years.
A common symptom of wintertime SAD is increased appetite, especially for sweets and starches, often with a significant weight gain. Patients may also experience "leaden paralysis" in which there is a very heavy feeling in the arms or legs. Decreased energy, extreme fatigue, and oversleeping are other symptoms. Poor concentration, irritability, increased sensitivity to social rejection and avoidance of social settings also may occur. There is a milder form known as S-SAD that is even more prevalent (10-20% in US). Lastly, there is a much less common "spring-onset" SAD characterized by weight loss, poor appetite and insomnia.
Though wintertime SAD is not well understood it is believed that decreased daylight is a very important factor. Melatonin, a sleep-related hormone made by the brain has been linked to depression. It is produced in larger amounts in the dark and so may be produced more in winter. There is very good evidence that serotonin, another hormone made in the brain, is decreased in dark conditions. Low amounts of serotonin have been linked to depression. The amount of serotonin made by the brain increases very rapidly in response to light - and so can vary day to day.
The two primary treatments for wintertime SAD are light therapy and antidepressant medication. Bright light therapy, administered with a specially made light box, has been shown to suppress the brain's secretion of melatonin. Many patients respond to this treatment. Tanning beds are not useful for SAD and use light sources high in UV rays which can be harmful to the eyes and skin. Light therapy, as well as medication, should only be used under the supervision of your physician. Other potentially helpful interventions available to everyone include taking daily walks outside, enhancing indoor lighting, setting a timer on a bedroom light to go on early in the morning, and using a "dawn simulator" for a more naturalistic artificial dawn.
1. National Mental Health Association 2005. Seasonal Affective Disorder fact sheet.
2. Familydoctor.org 2002 Seasonal Affective Disorder
3. Up-To-Date 2004, Seasonal Affective Disorder
4. Lancet 2002; 360:1840-42. Effect of sunlight and season on serotonin turnover in the brain.