Dark Triad
© AlamyResearch suggests people who like staying up late tend to have more evil personality traits.
Psychologists have found that people who are often described as "night owls" display more signs of narcissism, Machiavellianism and psychopathic tendencies than those who are "morning larks".

The scientists suggest these reason for these traits, known as the Dark Triad, being more prevalent in those who do better in the night may be linked to our evolutionary past.

They claim that the hours of darkness may have helped to conceal those who adopted a "cheaters strategy" while living in groups.

Some social animals will use the cover of darkness to steal females away from more dominant males. This behaviour was also recently spotted in rhinos in Africa.

Dr Peter Jonason, a psychologist at the University of Western Sydney, said: "It could be adaptively effective for anyone pursuing a fast life strategy like that embodied in the Dark Triad to occupy and exploit a lowlight environment where others are sleeping and have diminished cognitive functioning.

"Such features of the night may facilitate the casual sex, mate-poaching, and risk-taking the Dark Triad traits are linked to.

"In short, those high on the Dark Triad traits, like many other predators such as lions, African hunting dogs and scorpions, are creatures of the night."

Dr Jonason and his colleagues, whose research is published in the journal of Personality and Individual Differences, surveyed 263 students, asking them to complete a series of standard personality tests designed to test their score for the Dark Triad traits.

They were rated on scales for narcissism, the tendency to seek admiration and special treatment; Machiavellianism, a desire to manipulate others; and psychopathy, an inclination towards callousness and insensitivity.

To test each, they were asked to rate their agreement with statements like: "I have a natural talent for influencing people", "I could beat a lie detector" and "people suffering from incurable diseases should have the choice of being put painlessly to death".

The volunteers were also asked to complete a questionnaire about how alert they felt at different times of the day and how late they stayed up at night.

The study revealed that those with a darker personality score tended to say they functioned more effectively in the evening.

They also found that those who stayed up later tended to have a higher sense of entitlement and seemed to be more exploitative.

They could find no evidence, however, that the traits were linked to the participants gender, ruling out the possibility that the tendency to plot and act in the night time had its roots in sexual evolution.

Previous research has suggested that people who thrive at night tend also to be more intelligent.

Combined with the other darker personality traits, this could be a dangerous mix.

Notorious leaders including Adolf Hitler and Josef Stalin are among those who are known to have stayed up late at night and had displayed these dark personality traits.

Other night owls such as Bill Clinton, the former US president, and Winston Churchill, the former British prime minister, have often been accused of showing less extreme elements of at least some of these traits.

However, there are some examples of night owls where these negative traits may be harder to spot.

President Barack Obama is reputed to a night owl, as was Elvis Presley and James Joyce.

Famous morning larks include Napoleon, Ernest Hemingway and George W Bush.

Dr Jonason added: "We felt that providing evidence of such an odd relationship would better make our case that being high on the Dark Triad might be adaptive in selecting certain niches.

"I think it is too simplistic to think that people are either/or. People everywhere can exhibit these traits.

"Those who want to exploit others should have a bias towards choosing the night-time niche because the night time means fewer people are awake to detect exploitation."

Other research has shown that evening types tend to b more extrovert and creative types such as poets, artists and personalities.

Morning types were often found in roles like civil servants and accountants.

Findings from Surrey University have suggested that people's tendency to be night owls or morning larks is determined by their genes.

Professor Jim Horne, a sleep researcher at Loughborough University, said: "There are quite a lot of things associated with the time we go to bed and get up.

"People who are shorter sleepers tend to be a bit more manic about things and tend to take risks and have delusions of grandeur.

"Morning types are more rigid and less adaptable in their body clocks while evening types are better able to deal with shift work and jet lag.

"In reality, the majority of people are neither one or the other. Genes probably only account for about 10 per cent of it, but whether we are night owls or morning larks tends to change with age.

"We tend to go to bed later when we are younger. Students also tend to be more full of bravado and so this may have influenced these results.

"It would be interesting to see if morning types are more trustworthy and more upstanding citizens because these are the people who get up to go to work on time and go to church perhaps."