SAD

Symptoms

The symptoms of SAD usually recur regularly each Winter, starting between September and November and continuing until March or April. A diagnosis can be made after three or more consecutive Winters of symptoms, which include a number of the following

Sleep problems:	Usually desire to oversleep and difficulty staying awake but, in some cases, disturbed sleep and early morning wakening
Lethargy:	Feeling of fatigue and inability to carry out normal routine
Overeating:	Craving for carbohydrates and sweet foods, usually resulting in weight gain
Depression:	Feelings of misery, guilt and loss of self-esteem, sometimes hopelessness and despair, sometimes apathy and loss of feelings
Social problems:	Irritability and desire to avoid social contact
Anxiety:	Tension and inability to tolerate stress
Loss of libido	Decreased interest in sex and physical contact
Mood changes	In some sufferers, extremes of mood and short periods of hypomania (overactivity) in spring and autumn.

Most sufferers show signs of a weakened immune, system during the Winter, and are more vulnerable to infections and other illnesses.

SAD symptoms disappear in Spring, either suddenly with a short period (e.g., four weeks) of hypomania or hyperactivity, or gradually, depending on the intensity of sunlight in the Spring and early Summer.

In sub-syndromal SAD, symptoms such as tiredness, lethargy, sleep and eating problems occur, but depression and anxiety are absent or mild.

SAD may begin at any age but the main age of onset is between 18 and 30 years.

It occurs throughout the northern and southern hemispheres but is extremely rare in those living within 30 degrees of the Equator, where daylight hours are long, constant and extremely bright.