The exact cause of psychosis is not known but as it occurs in a variety of mental and physical disorders it's likely to have several different causes. There are many theories about what causes psychosis but there are no definite answers. It is believed that some people have a vulnerability to developing psychosis due to various biological and genetic risk factors and that stress, in combination with this vulnerability, can bring on an episode of psychosis.
Stress can be defined as a major life event such as a bereavement or change in social circumstances like moving house or unemployment. Stress can also be described as daily hassles such as not getting tasks done on time or worrying about a financial problem. The impact of stress on an individual with psychosis has been well documented and it has been noted that stress is a significant factor at first onset and also at subsequent relapse.