If you have employees who are early risers, you may want to keep an eye on their behavior near the end of the day. And if you have night owls on your team, don't give them work in the morning that depends on making ethical decisions.

In two recent studies, researchers found a correlation between energy levels, chronotype (what time of day a person functions best) and unethical behavior. Christopher M. Barnes, an assistant professor of management at the University of Washington's Foster School of Business; Brian Gunia, an assistant professor of management at Johns Hopkins University's Carey Business School; and Sunita Sah, an assistant professor of strategy, economics, ethics and public policy at Georgetown University's McDonough School of Business, found that larks (morning people) and owls (night people) compromise their ethics during their opposite chronotype hours.

"Because their energy levels should follow different patterns, and this energy is crucial for resisting temptation, we expected larks to be more unethical late at night than early in the morning, and owls to be more unethical early in the morning than late at night," the trio write in Harvard Business Review.

As a leader, it's important to discard the notion that good people typically do good things and bad people typically do bad things, the researchers write. "There is mounting evidence that good people can be unethical and bad people can be ethical, depending on the pressures of the moment. For example, people who didn't sleep well the previous night can often act unethically, even if they aren't unethical people."

During the first study, which focused on morning behavior, the researchers took participants into a lab and gave them a simple task in which they were paid more money for each additional part that they said they completed. Participants thought their work was anonymous, and believed they could cheat to earn more money, but the researchers tracked each individual. "Consistent with our prediction, since these were morning sessions: Night owls were more likely to cheat than larks," Barnes, Gunia, and Sah write.

In the second study, the researchers randomly assigned a new set of participants to early-morning sessions or late-night sessions for a die-rolling experiment. The participants were told they would get paid more money if they rolled higher numbers.

The findings proved the researchers' hypothesis: Larks who rolled during the night sessions reported higher rolls than larks who rolled in the morning, while owls reported higher rolls during morning sessions than the ones who rolled at night. 

"The important organizational takeaway from these findings is that individuals may be more likely to act unethically when they are 'mismatched'--that is, making a decision at the wrong time of day for their own chronotype," Barnes, Gunia, and Sah write. "Managers should try to learn the chronotype (lark, owl, or in between) of their subordinates and make sure to respect it when deciding how to structure their work. Managers who ask a lark to make ethics-testing decisions at night, or an owl to make such decisions in the morning, run the risk of encouraging rather than discouraging unethical behavior."