SAD was first described in 1985 and many scientists remain sceptical. However, all mammals display seasonal differences in their physiology, and doctors report success with sufferers treated with light therapy. Melatonin, produced by the pineal gland in the brain, which helps to maintain bodily rhythms, has also been found to be far lower in SAD sufferers than non-depressed people.
One in 100 people suffers from depression during the winter months which is so severe it can be disabling, a psychiatrist said yesterday. Dr Chris Thompson, an expert in Seasonal Affective Disorder or SAD, at Southampton University, said sufferers showed impaired function of a chemical in the brain during the winter. In the summer this appeared to be restored.