Alternatively, people with SAD may have trouble regulating their levels of serotonin, a neurotransmitter that influences mood.
Finally, research has suggested that people with SAD also may produce less Vitamin D in response to sunlight; vitamin D is believed to play a role in serotonin activity.
Seasonal Affective Disorder, or SAD, is a type of recurrent major depressive disorder in which episodes of depression occur during the same season each year.
This condition is sometimes called the "winter blues," because the most common seasonal pattern is for depressive episodes to appear in the fall or winter and remit in the spring.
Either type of SAD may also include some of the symptoms that occur in major depression, such as feelings of guilt, a loss of interest or pleasure in activities previously enjoyed, ongoing feelings of hopelessness or helplessness, or physical problems such as headaches and stomach aches.
Symptoms of SAD tend to recur at about the same time every year.Darkness stimulates the production of melatonin, preparing the body for sleep.As the winter days get shorter and darker, melatonin production in the body increases and people tend to feel sleepier and more lethargic.His doctor ran many tests, but the results all came out normal.Owens wound up seeing a psychiatrist, who diagnosed depression, and prescribed various stimulants and antidepressants.Doctors first noticed this opposite, annual winter depression, 150 years ago, but the condition remained a theory until the early 1980's, when researchers began linking the darkening of people's winter moods to the lack of sunlight from November through March.Today, this condition is known as Seasonal Affective Disorder (SAD).To be diagnosed with SAD, an individual must meet criteria for major depression coinciding with specific seasons for at least two years.The individual must experience seasonal depressions much more frequently than any non-seasonal depressions.Some people experience symptoms severe enough to affect quality of life, and 6 percent require hospitalization.Many people with SAD report at least one close relative with a psychiatric disorder, most frequently a severe depressive disorder (55 percent) or alcohol abuse (34 percent).