Depression is a common illness – far more common than is usually realised, it being estimated that about 20% of adults will experience this condition sometime during their lives.

In common parlance, depression is a word that we use to describe our feelings when we are sad – if we are "down in the dumps" or "blue", or as we might say colloquially, "feeling a bit puss". Most of us will feel like this now and then, reacting to some depressing situation in our day to day life such as the death of someone we love or the loss of our job. Feelings like this can actually be beneficial because they can help you to realise that something constructive must be done to change the situation in which you find yourself.

Medically, however, the word Depression is quite different to these feelings of sadness which are part of the usual emotional ups and downs of life. Clinical Depression lasts longer than an episode of "the blues" – being accompanied by feelings of hopelessness and helplessness that can have serious negative effects on your outlook. This type of Depression is not just about an episode of feeling sad or emotionally down – it is a medical disease that affects the way you think and behave.

Understanding the difference between those feelings of sadness which are a natural reaction to a difficult event in our lives and the clinical condition of Depression is important. While the feelings brought on by grief can be quite intense and last a long time, they help the person to adjust, develop new meaning in life and move on after the loss. Clinical Depression in contrast is an illness – characterised by symptoms such as

* feeling irritable or sad most of the time and lacking the joy in life

* feeling tired all the time

* being reluctant to undertake any activity because it is too much of an effort

* feeling unworthy as if you are a major burden to those around you

* having trouble falling asleep or waking up in the early hours of the morning

These relentless feelings of helplessness and hopelessness (which Winston Churchill, who suffered from Depression himself, used to call "The Black Dog") are what make the condition so difficult to handle. Sometimes they can be quite frightening, even evoking thoughts of death and suicide. Family and friends generally do not understand that your depression is caused by a real illness and that you have no choice in the matter – in fact they may become frustrated and critical, nagging you to just "snap out of it".

Depression is not an illness that you can just "snap out of" - although it certainly can be treated successfully.

The first step is to recognise that the symptoms you (or someone close to you) are experiencing are manifestations of a common medical condition which is amenable to treatment. Talking about these feelings with someone close to you that you can trust is important, as is seeking professional help from a doctor, psychologist or qualified counsellor.

There are many ways – such as counselling, psychotherapy, medications – that are available to treat Depression. Which one (or more) of these methods of treatment is most appropriate for you is best decided in co-operation with a health professional.

What is important is to realise that the symptoms you are experiencing are the manifestation of an illness which needs treatment – and to seek professional help, because Depression is not a hopeless situation but a curable illness.