Who gets Seasonal Affective Disorder?
At least 1 in 50 people in the UK are thought to have SAD. Many more, perhaps as many as 1 in 8 people, have 'winter blues' - a less severe form of the condition. SAD is less common in countries near to the equator where the hours of sunlight are more constant and bright throughout the year.
SAD usually first begins between the ages of 20 to 30, but it can develop at any age. It affects four times as many women as men.
What causes seasonal affective disorder?
The exact cause is not clear. The amount of sunlight affects the number of nerve messages which you send from the eyes to certain parts of the brain. The activity of nerve messages caused by sunlight affect the level of certain brain chemicals (such as serotonin) and hormones (such as melatonin). These chemicals and hormones are thought to affect your 'mood'. So, with less sunlight in the winter months, changes in the balance of certain chemicals and hormones may affect your mood and trigger a depression.
Your genetic makeup may be important too as some people inherit a tendency to develop SAD. About 1 in 7 first degree relatives (mother, father, child, brother, sister) of people with SAD are also affected.
- Next: What are the symptoms of SAD?
More on SAD
- Ten ways to fight depression
- How sun can help SAD
- Read in-depth information on depression
- Tips on coping with depression
- How a lightbox changed Nikki's life
- Have you suffered from SAD? Share your experiences


