Feeling sad is often a normal human reaction to events, but when these feelings do not go away naturally and begin to interfere with your life, this is described as depression.
Depression can present itself in many different ways. It may include a range of problems affecting your feelings (such as feeling numb or helpless), your behaviour (avoiding social situations), your thoughts (such as lots of negative thoughts or thinking about suicide) and your body (such as changes in appetite, problems sleeping and having no energy).
There are many possible causes of depression, for example, loss, difficult life events, childhood experiences, side effects of medications and diet, amongst others. It can also occur alongside other problems such as post-traumatic stress disorder.