Everyone occasionally feels blue or sad, but these feelings are usually fleeting and pass within a couple of days. When a person has depression it interferes with daily life, normal functioning, and causes pain for both the person with the disorder and those who care about him/her.

The below list covers some but not all types of depression. Symptoms of depression can range from relatively minor (but still disabling) through to very severe.

Major Depression/Clinical Depression
Major Depression or Clinical Depression is the more severe type of depression where the symptoms interfere with the ability to work, sleep, study, eat, and enjoy life. Major Depression is marked by a depressed mood most of the day, particularly in the morning, and a loss of interest in normal activities and relationships; symptoms that are present every day for at least 2 weeks.

Melancholia Depression
Melancholia Depression is the classic form of biological depression.  It is a term used to describe a severe form of depression where many of the physical symptoms of depression are present. One of the major changes is that the person can be observed to move more slowly. The person is also more likely to have a depressed mood that is characterised by a complete loss of pleasure in everything, or almost everything.

Non-melancholic Depression/Situational Depression
Non-melancholic Depression is associated with psychological causes, and is very often linked to stressful events in a person’s life, and/or in conjunction with the individual’s personality style.  This type of depression can occur when someone is having trouble managing a stressful event in their life, such as a death in the family, divorce, or losing a job.

Persistent Depressive Disorder (Dysthymic disorder)
The symptoms of Persistent Depressive Disorder are similar to those of major depression but are less severe. However, in the case of Persistent Depressive Disorder the symptoms last longer. A person has to have this milderfor more than two years to be diagnosed with persistent depressive disorder.

Seasonal Affective Disorder (SAD)
Seasonal Affective Disorder is a type of depression that has a seasonal pattern that is characterized by the onset of depression during the winter months when there is less natural sunlight.  A person with Seasonal Affective Disorder is more likely to experience lack of energy, sleep too much, overeat, gain weight and crave for carbohydrates.  SAD also generally lifts during spring and summer. SAD is very rare in Australia and more likely to be found in countries with shorter days and longer periods of darkness, such as in the cold climate areas of the Northern Hemisphere. 

Bipolar Disorder
Bipolar Disorder used to be known as ‘manic depression’ because the person experiences periods of depression and periods of mania, with periods of normal mood in-between. Mania is like the opposite of depression and can vary in intensity; symptoms include feeling great, having lots of energy, having racing thoughts and little need for sleep, talking fast, having difficulty focusing on tasks, and feeling frustrated and irritable.

Atypical Depression
Atypical Depression is different to the usual persistent sadness experienced with typical depression. In contrast, Atypical Depression is associated with improved mood when something positive happen. Other symptoms of this type of depression include increased appetite, sleeping more than usual, feeling of heaviness in your arms and legs, and oversensitivity to criticism.

Male Hormonal Depression/Testosterone-Deficiency Depression
This type of depression is associated with the male ageing process and can sometimes occur in men during their 30’s, 40’s or 50’s as their body’s production of testosterone may begin to slow.  This gradual decline can produce symptoms such as erectile dysfunction, decreased libido, increase in irritability, feeling tired, difficulty with concentration and memory loss, and sleep problems.

Male Depressive Disorder/Covert Depression
Men are less likely to show more typical signs of depression such as sadness. Depression in men may cause them to keep their feelings hidden. Instead of expressing a depressed mood, they may seem more irritable and aggressive. Men are more likely to recognise and describe the physical symptoms of depression (such as feeling tired or losing weight) than women.

Men may acknowledge feeling irritable or angry, rather than saying they feel low. Depressed men will often lose interest in work, sport, sex, going out, or other things they used to enjoy. Other behaviours in men that could be signs of depression, but not recognized as such, include escapist behaviour, such as spending a lot of time at work or on sports; alcohol or substance abuse; controlling, violent or abusive behaviour; irritability or inappropriate anger, and risky behaviour, such as reckless driving