BBC NEWS | Health | Depression.
Depression is a common mental illness which is estimated to affect up to one in five Britons at some point in their lifetime and to cost the UK about £8bn a year in medication, benefits and lost working days.
It can strike at any age and the feelings of hopelessness and helplessness attached to it can make it difficult for people to carry out their normal activities.
It can be more or less severe and symptoms are often varied, making it often hard to diagnose.
It is thought that some individuals may be more prone to depression, whether because of life experiences, their body chemistry or genetically inherited conditions.
Those who have suffered from depression include Sir Winston Churchill and Florence Nightingale.
