London - 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.

Study author Dario Maestripieri, professor in Comparative Human Development at the University of Chicago, believes that the link between night owls and risky behaviour has roots in evolutionary strategies for finding mates.

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.” - Daily Mail