Depression, like dyslexia and “Yuppie flu”, is one of those fashionable diseases that have no symptoms except what the sufferer feels.

Now Professor Jerome Wakefield of New York University has said that sadness and depression are essential tools of evolution that prompt “sufferers” to become high achievers in life. He cites Winston Churchill, Beethoven, Abraham Lincoln and Isaac Newton as depressives who made good.

Wakefield says: “When you find something this deeply in us biologically, you presume it was selected because it had some advantage, otherwise we wouldn’t have been burdened with it. We’re fooling around with part of our biological makeup.”

He further believes that medical diagnoses of depression and its treatment with powerful drugs, like Prozac, is an unnecessary and dangerous fad. His book, The Loss of Sadness: How psychiatry transformed normal sorrow into depressive disorder states that sadness helps us learn from our mistakes. “I think one of the functions of intense negative emotions is to stop our normal functioning — to make us focus on something else for a while.”

So, if you are feeling down, consider that a deep part of yourself may be attempting to convey something to you.

At least try to find out what it is before heading for the medic’s surgery.