How Common is SAD?

SAD is surprisingly common. There have been no specific studies that I am aware of that show the true extent of seasonal affective disorder. Some studies show up to 20% of people may suffer from some form of SAD. SAD affects more men than women. However, when a man is diagnosed with SAD, they experience more severe symptoms.

Most people will have experienced "winter blues". However, if accompanied by other symptoms such as fatigue or lethargy, it is more likely SAD than normal winter blues. Many people with the condition do not seek medical help.

Winter-onset depression is the most common. The shorter daylight hours may be the cause. People in northern regions are more likely to suffer - due to the shorter days the further north you go. Most people affected will only show mild symptoms of depression.

Summer-onset depression is rarer - believed to be lower than 1% of the population. No detailed study to understand summer-onset depression has been undertaken.