“Early to bed and early to rise, makes a [woman] healthy, wealthy, and wise,” and don’t forget more likely to be married, and well rested. According to a study published in the journal Evolutionary Psychology, night-owl women — those who prefer to stay up late into the night and wake up late in the morning — are more likely to engage in the same risk-taking tendencies, such as having more sex and short-term relationships, similar to night-owl men, due to high cortisol levels.

“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,” said Dario Maestripieri, lead author of the study and professor in Comparative Human Development at the University of Chicago, in the school’s news release. These risk-taking behaviors are associated with the increase in cortisol levels — usually associated with high energy, arousability, stress, and even cognitive function — which enable men and women to be more active in the evening hours. Maestripieri believes preferences for being a night owl or an early morning person are attributed in part to biology and genetic inheritance, although environmental factors such as shift work or child-rearing could also be influential factors.

At the University of Chicago, Maestripieri investigated whether eveningness, or being a night owl, is associated with short-term relationship orientation, higher risk taking, and higher testosterone or cortisol. Data was drawn from an earlier study of more than 500 graduate students at the University of Chicago Booth School of Business. The initial study assessed the financial risk aversion among male and female students, and found men are more willing to take financial risks than women. However, the women with high testosterone levels were more similar to men in financial risk-taking.

Maestripieri decided to elaborate on the previous study and unveil why men take more risks than women, and if sleep patterns had any influence on these tendencies. The sample size for the recent study comprised a total of 100 males and 91 females. Researchers assessed amount of sleep, relationship status, number of previous sexual partners, and overall risks and sleep patterns.

The findings revealed men had higher cortisol and testosterone levels than women. However, night-owl women had cortisol levels comparable to night-owl and early-morning men. Night-owl men were also found to have twice as many sexual partners compared to their male early bird counterparts. Maestripieri believes high cortisol levels could be a biological biomarker that explains the higher risk-taking behaviors in night owls.

“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,” Maestripieri said, according to Science Daily. He believes being active in the evening hours facilitated our needs to engage in social and mating activities earlier in our evolutionary history. A surprising finding by the researchers was that men were more likely to consider themselves as night-owls, and slept less.

Although it is not yet know how and why, men and women tend to differ in their sleeping patterns after puberty, but these differences subside after women reach menopause. Surveys administered by the National Center on Sleep disorders Research, a division of the National Institutes of Health, have found women suffer from insomnia two to three times more than men, but men are twice as likely to suffer from sleep apnea. The statistical differences could be due to doctors not completely understanding sleeping patterns in both sexes, which could influence diagnosis.

While less sleep may mean more one-night stands and short-term relationships, it could also jeopardize your health and lead to brain damage. Perhaps early birds are ahead of the mating game and do catch the right worm.

Sources:

Maestripieri D. Night owl women are similar to men in their relationship orientation, risk-taking propensities, and cortisol levels: Implications for the adaptive significance and evolution of eveningness, Evolutionary Psychology. 2014.

Maestripieri D, Sapienza P, and Zingales L. Gender differences in financial risk aversion and career choices are affected by testosterone. Proceedings of the National Academy of Sciences. 2009.