Seasonal affective disorder, sometimes called SAD or winter depression, is a type of depression that comes and goes with the seasons. For most people affected, symptoms begin in autumn and winter, when daylight is shorter, and lift in spring and summer. It is thought to be linked to reduced light affecting the body clock and mood-regulating brain chemicals.
Symptoms are similar to other depression and can include low mood, low energy, sleeping more than usual, craving carbohydrates, weight gain, and loss of interest in activities. The seasonal timing, repeating year after year, is the distinguishing feature. A less common form occurs in summer.
Helpful approaches can include getting as much natural daylight as possible, regular exercise, and, for some people, light therapy using a special lamp, as well as talking therapy or medication where appropriate. Because the symptoms overlap with other conditions, it is best to see a doctor for an assessment rather than self-diagnosing. Seek urgent help if low mood becomes severe or you have any thoughts of self-harm.