Maestripieri's study suggests high cortisol levels may be one of the biological mechanisms explaining higher risk-taking in night owls.
Maestripieri 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. Higher cortisol can be associated with higher cognitive function, he said, and some studies show that high-achieving, successful people have high cortisol levels.
More men than women consider themselves night owls, the study found, and men sleep less overall. 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, Maestripieri said.
The link between the night-owl tendency and risky behavior could have roots in evolutionary strategies for finding mates, Maestripieri said.
"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 that occur outside of committed, monogamous relationships," Maestripieri 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." The findings that night owls are less likely to be in long-term relationships and that male night owls report a higher number of sexual partners offer some support to this hypothesis, he said.
Maestripieri said he has replicated the main result of higher risk-taking in night owls with an expanded, non-student population and hopes to
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University of Chicago