According to new research, your sleep patterns say a lot about your romantic life.
A study out of the University of Chicago analyzed the effects of sleep patterns on human behavior and found that male and female "night owls" (NOs) -- defined as people who go to sleep late and wake up late -- were likely to be having more sex than their "early morning" (EM) counterparts, but were less likely to be in committed, long-term relationships.
Researchers theorized that this type of short-term mating at night -- preferable to those who stay up late -- evolved from our ancestors.
"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," study author Dario Maestripieri said in a press release.
The researchers also found that female night owls related more closely to males in their behavior than to early morning females; they were more likely to be single, sexually promiscuous and were bigger risk takers. One reason for this? The female NOs were found to have the same cortisol levels as the men, and cortisol is linked with arousability, high energy, stress and cognitive function.
Maestripieri, a professor in Comparative Human Development, conducted the study using data from over 500 graduate students. His results were published in the February edition of Evolutionary Psychology.
Professor Maestripieri told The Huffington Post that he hopes this research can enlighten people as to why they do the things they do.
"Many people can self-identify as an early bird or a night owl. This study helps people understand why their sleep preferences are associated with certain behavioral and personality characteristics." he said.