'Night Owls' Tend To Be Single And Fond Of 'Short Flings'

People who prefer to stay up late are more likely to be risk-takers and have one-night stands, a study has shown.

The research found so-called ‘night owls’ –  those who prefer to stay up late into the night and wake up late in the morning – tend to be single and are more likely to jump in and out of short-term relationships.

Male night owls had twice as many sexual partners than male ‘early birds’.


In the study, 211 volunteers gave saliva samples to test their levels of the hormones cortisol and testosterone.

These were measured both before and after the volunteers took a test to find out how likely they were to take risks with money.

The participants also told researchers whether they liked to take risks, as well as their sleep patterns.

The research, published in the journal Evolutionary Psychology found that night owls tend to have higher levels of cortisol, which is associated with high energy, arousal and risk-taking.

The study was led by Dario Maestripieri, professor in Comparative Human Development at the University of Chicago.

He said: 'Night owls, both males and females, are more likely to be single or in short-term romantic relationships versus long-term relationships, when compared to early birds.

'In addition, male night owls reported twice as many sexual partners than male early birds.'

Prof Maestripieri wanted to explore why men take more risks than women. He was curious whether sleep patterns have any influence on these tendencies, through an association with differences in personality and in novelty-seeking.

The study participants (110 males and 91 females) provided saliva samples to assess their levels of cortisol and testosterone.

Those levels were measured before and after participants took a test of their tendencies for financial risk. The participants also described their own willingness to take risks and gave information about their sleep patterns.

Men had higher cortisol and testosterone levels than women; however, night-owl women had cortisol levels comparable to night-owl and early-morning men.

Prof Maestripieri’s study suggests high cortisol levels may be one of the biological mechanisms explaining higher risk-taking in night owls.

He explains that some people have chronically high cortisol levels regardless of stress, which is known to increase cortisol for short periods of time.

 These people have high metabolism, high energy and arousability. High cortisol can be associated with higher cognitive function, he said, and some studies show high-achieving, successful people have high cortisol levels.

More men than women consider themselves night owls, the study found, and men sleep less overall.

Prof Maestripieri said preferences for being a night owl or early morning person are due in part to biology and genetic inheritance, but also can be influenced by environmental factors such as shift work or child-rearing.

Gender differences in sleep patterns emerge after puberty and become weaker or disappear after women reach menopause, the academic said.

Prof Maestripieri believes that the link between night owls and risky behaviour has roots in evolutionary strategies for finding mates.

'From an evolutionary perspective, it has been suggested that the night-owl trait may have evolved to facilitate short-term mating, that is, sexual interactions outside of committed, monogamous relationships,' he said.

'It is possible that, earlier in our evolutionary history, being active in the evening hours increased the opportunities to engage in social and mating activities, when adults were less burdened by work or child-rearing.'