What is depression?

The word ‘depression’ is often used to describe the feelings of sadness which all of us experience at some stage of our lives. It is also a term used to describe a form of mental illness called clinical depression.

Because depression is so common, it is important to understand the difference between unhappiness or sadness in daily life and the symptoms of clinical depression.

When faced with stress, such as the loss of a loved one, relationship breakdown or great disappointment or frustration, most people will feel unhappy or sad. These are emotional reactions which are appropriate to the situation and will usually last only a limited time. These reactions are not regarded as clinical depression, but are a part of everyday life.

The term ‘clinical depression’ describes not just one illness but a group of illnesses characterised by excessive or long-term depressed mood which affects the person’s life. Clinical depression is often accompanied by feelings of anxiety. Whatever the symptoms and causes of depression, treatment is very effective.

What are the main types of depressive illness?

Adjustment disorder with depressed mood

People with this illness are reacting to distressing situations in their lives (e.g. the failure of a close relationship or loss of a job) but to a greater degree than is usual.

This depression is more intense than the unhappiness experienced in daily life, it lasts longer and the symptoms often include anxiety, poor sleep and loss of appetite.

The time which this form of depression lasts may vary from weeks to years.

It usually goes away when the cause is removed or when the person finds a new way to cope with the stress. Many people require intensive professional help and treatment to overcome this type of depression.

Post-natal depression

The so-called baby blues affect about half of all new mothers. They feel mildly depressed, anxious, tense or unwell, and may have difficulty sleeping even though they are tired and lethargic most of the time. This type of depression may last only hours or for a few days, then disappear.

However, in about 10 per cent of mothers this feeling of sadness develops into a serious disorder called post-natal depression. Mothers with this illness find it increasingly difficult to cope with the demands of everyday life.

They can experience anxiety, fear, despondency and sadness. Some mothers have panic attacks or become tense and irritable. There may be a change in appetite and sleep patterns.

A severe, but rare form of post-natal depression is called puerperal psychosis. The woman is unable to cope with her everyday life and can be disturbed in her thinking and behaviour.

Depressive episode

This is, in general, a more severe form of clinical depression. It can come on without apparent cause, although in some cases a distressing event might trigger the condition.

The cause is not well understood but is believed to be associated with a chemical imbalance in the central parts of the brain.

A depressive episode can develop in people who have coped well with life, who are good at their work and happy in family and social relationships.

They become low-spirited, lose their enjoyment of life and suffer disturbed sleep patterns. People experiencing a depressive episode lose their appetite, lack concentration and energy and may lose weight. Feelings of guilt are also common.

Sometimes their feelings of hopelessness and despair can lead to thoughts of suicide.

The most serious form of this type of depression is called psychotic depression. During this illness, the person loses touch with reality, may stop eating and drinking and may hear voices saying they are wicked or worthless and deserve to be punished.

Others develop false beliefs (delusions) that they have committed bad deeds in the past and deserve to be punished, or that they have a terminal illness such as cancer, despite there being no medical evidence.

A depressive episode or a psychotic depression are serious and painful illnesses with real risks to the person’s life and well-being. Professional assessment and treatment is always necessary and in severe cases, hospitalisation may be required initially.

Bipolar mood disorder (previously called manic depression)

A person with bipolar mood disorder experiences depressive episodes alternating with periods of mania involving extreme happiness, over-activity, rapid speech, a total lack of inhibition and, in more serious instances, delusions of grandeur.

Sometimes only periods of mania occur, without depressive episodes.

For more information on bipolar mood disorder, read the Mental Health Information brochure What is bipolar mood disorder?

What causes depression?

Often there are many interrelated factors associated with depression:


It is well established that the tendency to develop depression runs in families. This is similar to a predisposition to other illnesses, such as heart disease and high blood pressure.

Biochemical imbalance

As already stated, depressive episodes are thought to be due in part to a chemical imbalance in the brain. This can be corrected with anti-depressant medication.


Depression is associated with stress after personal tragedies or disasters. It is more common at certain stages of life, such as at childbirth, menopause and retirement, and common in young adults, women and people with physical health problems.


People with certain personality characteristics are more prone to depression.

Depression occurs more commonly in people who are sensitive, emotional and prone to experience feelings which are upsetting to them.

Perfectionists who set high standards for themselves and others, and who find it difficult to adjust their ideas and standards to changing circumstances, are often easily depressed. Also, those who are very dependent on others are susceptible to depression if they are let down.

Learnt response

In some cases, people exposed to repeated losses or stress throughout their lives lose their optimism and feel helpless and depressed.

What treatment is available?

People experiencing feelings of sadness which have persisted for a long time or which are affecting their life to a great extent, should contact their family doctor or community health centre.

Modern treatments for depression can help the person return to more normal feelings and to enjoy life. Treatment depends on each person’s symptoms, but will take one or more of the following forms:

Psychological interventions help individuals understand their thoughts, behaviours and interpersonal relationships.

General supportive counselling assists people to sort out practical problems and conflicts and helps them understand the reasons for their depression.

Anti-depressant medications relieve depressed feelings, restore normal sleep patterns and appetite and reduce anxiety. Unlike tranquillisers, anti-depressant medications are not addictive. They slowly return the balance of neurotransmitters in the brain, taking 1-4 weeks to achieve their positive effects. Specific medications help to manage mood swings. For more information, read the Mental Health Information Brochure What is bipolar mood disorder?

Lifestyle changes, such as physical exercise, assist people who suffer from depression.For some severe forms of depression, electroconvulsive therapy (ECT), or shock treatment as it is sometimes misnamed, is a safe and effective treatment. It may be life saving for people at high risk of suicide or who, because of the severity of their illness, have stopped eating and drinking and will die as a result.

Where to go for help

  • Your general practitioner.
  • Your community health centre.
  • Your community mental health centre. For information on services, check the Community Help and Welfare Services and 24-hour emergency numbers in your local telephone directory.