Narcissism can have its benefits as it adds mental toughness, a study by Queen's University Belfast has found.

New research found the personality trait can also lead to people feeling less stressed and being less vulnerable to depression than others.

Narcissistic personality disorder is characterised by a person believing there are special reasons that make them different, better or more deserving than others.

They may feel upset if people do not recognise their apparent achievements, resent other people's successes and get upset if other people do not put their needs above their own.

But narcissists may also suffer low self-esteem and can be described as vulnerable.

The new research, led by Queen's University Belfast, was published in the journals Personality and Individual Differences and European Psychiatry.

Dr Kostas Papageorgiou, from Queen's school of psychology, said: "Narcissism is part of the 'dark tetrad' of personality that also includes Machiavellianism, psychopathy and sadism.

"There are two main dimensions to narcissism - grandiose and vulnerable.

"Vulnerable narcissists are likely to be more defensive and view the behaviour of others as hostile, whereas grandiose narcissists usually have an over-inflated sense of importance and a preoccupation with status and power.

"Individuals high on the spectrum of dark traits, such as narcissism, engage in risky behaviour, hold an unrealistic superior view of themselves, are overconfident, show little empathy for others, and have little shame or guilt."