Seasonal affective disorder, or SAD, is a type of depression that affects a person during the same season each year. If you get depressed in the winter but feel much better in spring and summer, you may have SAD.
Anyone can get SAD, but it is more common in:
People who live in areas where winter days are very short or there are big changes in the amount of daylight in different seasons.
People between the ages of 15 and 55. The risk of getting SAD for the first time goes down as you age.
People who have a close relative with SAD.
What causes SAD?
Experts are not sure what causes SAD, but they think it may be caused by a lack of sunlight. Lack of light may upset your sleep-wake cycle and other circadian rhythms. And it may cause problems with a brain chemical called serotonin that affects mood.
What are the symptoms?
If you have SAD, you may:
Feel sad, grumpy, moody, or anxious.
Lose interest in your usual activities.
Eat more and crave carbohydrates, such as bread and pasta.
Sleep more and feel drowsy during the daytime.
Symptoms come and go at about the same time each year. For most people with SAD, symptoms start in September or October and end in April or May.