Women who are night owls show a similar high tendency toward risk-taking as men, according to a study by a University of Chicago researcher.
Research led by Dario Maestripieri, professor in Comparative Human Development at the University of Chicago, links sleep-wake patterns with personality traits and behavior. The study indicates that people who prefer late nights and late mornings—commonly called night owls—differ in meaningful ways from early risers, including in relationship orientation, novelty-seeking, and risk-taking.
“Night owls, both males and females, are more likely to be single or engaged in short-term romantic relationships than early birds,” Maestripieri said. “In addition, male night owls reported about twice as many sexual partners as male early birds.”
The published study, appearing in the February issue of Evolutionary Psychology, used data drawn from earlier research involving more than 500 graduate students at the University of Chicago Booth School of Business. That earlier work examined financial risk aversion and found men overall were more willing to take financial risks than women, although women with higher testosterone resembled men in their willingness to take financial risks.
To investigate whether chronotype (morningness versus eveningness) helps explain sex differences in risk-taking, Maestripieri and colleagues measured hormones and behavior in a sample of university participants. A subgroup of 201 participants—110 males and 91 females—provided saliva samples to measure cortisol and testosterone before and after taking a computerized financial risk-aversion task. Participants also completed self-reports about their willingness to take risks and described their usual sleep patterns.
The hormone measures confirmed that men had higher average cortisol and testosterone levels than women. Notably, however, female night owls had cortisol profiles comparable to both male night owls and early-morning males. The analysis suggests that elevated cortisol levels, rather than testosterone, may help explain why evening-oriented women showed risk-taking tendencies more similar to men.
Maestripieri notes that some individuals maintain chronically elevated cortisol levels independent of acute stress. These people tend to have higher metabolic rates, greater energy and arousability, and, in some studies, higher cognitive performance. Elevated cortisol is also observed in many high-achieving individuals, which could link physiological arousal to behavioral traits such as novelty-seeking and risk tolerance.
The study confirmed that eveningness is more common among men than women and that men reported sleeping less overall. Chronotype is shaped partly by genetics and biology but can be influenced by environment and life circumstances—shift work, parenting responsibilities, and other social demands can shift sleep patterns. Maestripieri observed that gender differences in chronotype typically appear after puberty and often diminish or disappear after women reach menopause.
From an evolutionary perspective, Maestripieri suggests eveningness may have conferred advantages for short-term mating strategies. Being active in the evening could historically have increased opportunities for socializing and mating during hours when day-time work and childcare duties were reduced. The findings that night owls are more often single and that male night owls report higher numbers of sexual partners provide partial support for this hypothesis.
Maestripieri reported that he has replicated the key finding—that night owls exhibit higher risk-taking tendencies—with a larger, non-student population and plans to publish those additional results.
Contact: Jann Ingmire – University of Chicago
Source: University of Chicago press release
Image Source: Image credited to Edward Hopper (1942) and The Art Institute of Chicago; public domain.
Original Research: Full open-access research titled “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” by Dario Maestripieri in Evolutionary Psychology.
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
Chronotype differences—whether a person is a morning type or an evening type—are relatively stable and partly inherited. Eveningness occurs more often in men, especially after puberty and before menopause in women. Some researchers have proposed that eveningness evolved recently and may favor short-term mating strategies. This pattern is linked with traits such as extraversion and novelty-seeking and, in men, a higher number of sexual partners. In this study, eveningness was associated with a greater likelihood of being single rather than in a long-term relationship for both sexes. Evening-oriented women showed higher risk-taking than early-morning women; this relationship was not explained by testosterone but appeared mediated by cortisol. Overall, female night owls resembled males more than early-morning females in cortisol profiles and risk behavior, offering support—particularly for women—for the idea that eveningness relates to behaviors useful in short-term mating strategies.