There are morning people and there are evening people; there is ethical behavior and there is unethical behavior. That much we know, and previous attempts to suss out how those categories overlap with each other pointed researchers toward what’s called the “morning morality effect.” The effect, written up in a study last year, suggests that people behave more ethically earlier in the day, the theoretical underpinning being that as a person grows drained from the day’s mounting obligations, they lose the wherewithal required to behave in a saintly manner.
This seems plausible enough, but another group of researchers wondered if the morning morality effect might overlook an element of existing sleep research: that people have specific “chronotypes,” meaning they’re predisposed to feeling alert at different times of day. (One's chronotype can change over the course of a lifetime.) The morning morality effect, they figured, doesn’t account for the portion of the population—roughly 40 percent—whose vitality blooms in the evening. These researchers conducted a study, to be published in the journal Psychological Science, that found that an evening person is roughly three times as likely to behave unethically in the morning than a morning person.
“An important aspect of this research is not that morning people are more moral, it's actually the match that's the most important thing. It's that morning people are more ethical in the morning, but evening people are more ethical in the evening,” says Sunita Sah, a co-author of the study and an assistant professor of business ethics at Georgetown University.
Classifying behavior as either ethical or unethical is a fraught process that might trouble some philosophers, but Sah and her co-authors turned to agreed-upon research tactics that would allow them to determine when a subject was lying to get ahead. The study included two different experiments, both of which involved self-reported results. In one, subjects were paid 50 cents for each math puzzle they completed in five minutes’ time, and in another, subjects rolled a die several times and were given lottery tickets in proportion to the dots on each roll. In both scenarios, several subjects lied about their results, and they did so along chronotypical lines.
The idea of scheduling “big ethical decisions” for certain times a day, based on your chronotype, seems impractical, but there are still things that can be done to accommodate these findings. Sah suggested that important meetings shouldn’t by default occur early in the morning, and would be better scheduled mid-day. She had another idea, based on her experience as a professor teaching undergraduates, who, given their typical age, tend to be evening people: “If we're setting exams at 8:00 in the morning, we might want to think about how many students are likely to cheat in those exams,” she says. Her findings might also add to the existing evidence that high school students might perform better if their school days started later.
Sah said she’s interested in exploring the effects of culturally-imposed sleep habits on ethical behavior. For example, when Daylight Savings Time goes into effect and people lose an hour of sleep, their moral compass might be, at least marginally, thrown out of whack. (This isn’t entirely implausible: Consider a 2009 study that found that, among miners, losing sleep to Daylight Savings increased the risk of having an accident the following Monday.)
Another unexplored phenomenon is napping. “Some cultures already have napping in the afternoon, siestas, which might mitigate some of the effects for morning people as the day goes on. It might renew their energy and make them more ethical,” Sah said. “Napping might refresh their cognitive abilities so that they could make a better decision at the end of the day."
This article originally appeared on The Atlantic.