Seasonal Affective Disorder (SAD) is a type of depression that has a seasonal pattern. The most common form of SAD is also called 'winter depression' because symptoms are worse in the winter months.
SAD affects most people in the winter
Symptoms of SAD tend to start from around September and are worse when the days are shortest (in December, January, and February).
By spring time, most people with SAD will improve and their symptoms usually disappear. Seasonal affective disorder can sometimes affect people in the summer rather than the winter, but this is rare and has different symptoms.
How common is SAD?
In the UK, about one in 50 people has SAD. The condition affects twice as many women than men. SAD can affect people of any age, but it is most common in those who are between 18-30 years of age.
Like any type of depression, SAD can be a difficult condition to live with. Symptoms can leave you feeling tired, lethargic, stressed and unhappy. However, there are a number of treatments and medications available that have proven to be very effective in treating SAD.
Winter blues is a milder form of SAD
When the sun is out, many people tend to feel happier and more energetic. When it is dark and gloomy, many of us feel more lethargic and less sociable. The amount of sunlight we get can affect our mood, appetite, energy levels and sex drive.
Up to one in eight people in the UK experience these milder symptoms of winter 'blues' (sub-syndromal SAD). However, for people with SAD, these feelings and symptoms are much more severe.
Studies around the world have shown that SAD becomes more common the further you are away from the equator. This suggests that SAD is linked to the change in the number of daylight hours through the year.
