People are more likely to lie or cheat when they're tired, study suggests

How likely you are to lie today could depend on how well you slept last night.

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According to recent studies from three researchers, including Brian Gunia, an assistant professor at Johns Hopkins University's Carey Business School, people not only become less productive when they are tired, but they are also more likely to lie, cheat, or act unethically in other ways. Gunia, Christopher M. Barnes of the University of Washington's Foster School of Business, and Sunita Sah of Georgetown's McDonough School of Business found that morning people tend to act more unethically at night, and night owls tend to act more unethically early in the day.

A full report of their findings will appear later this year in Psychology Today, but a summarized was published recently in the Harvard Business Review.

Over the past few years, management and psychology research has uncovered something interesting: both energy and ethics vary over time. In contrast to the assumption that good people typically do good things, and bad people do bad things, 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.

Our research started from this idea. Drawing from recent research indicating that people can become more unethical as the day wears on, we asked whether this plays out the same way for people who show different patterns of energy during the course of a day. Fatigue researchers have discovered that alertness and energy follow a predictable daily cycle that is aligned with the circadian process. However, different people may be shifted in their circadian rhythms. Some people are "larks" or "morning people" in that their circadian rhythm is shifted earlier in the day. They are most easily detected by their natural tendency to wake early in the morning. Others are "owls" or "evening people" and they are shifted in the opposite direction. Larks tend to get up early, and owls tend to stay up late.

The team conducted two studies. The first focused on behavior in the morning and offered payment to participants for solving tasks. The researchers found that "owls" were more likely to cheat by over-reporting how many tasks they had completed.

The second study had participants complete a die-rolling task during either a morning (7-8:30 a.m.) or night (midnight-1:30 a.m.) session and report what they had rolled to receive payment. Higher numbers were rewarded with larger payments. Statistically, the average of all rolls should be 3.5, but, the researchers wrote: "Consistent with our prediction, an interesting and statistically significant pattern emerged. Larks in the night session reported getting higher rolls (M=4.55) than larks in the morning sessions (M=3.86), and owls in the morning session reported higher rolls (M=4.23) than owls in the night sessions (3.80)."

In other words, the night owls were more likely to lie in the morning, and the morning people were more likely to lie at night.

There is an important organizational takeaway from these studies, the researchers conclude—that individuals are more likely to act unethically when they are making decisions at a time of day that doesn't suit them.

"Managers who ask a lark to make ethics-testing decisions at night, or an owl to make such decisions in the morning," they write, "run the risk of encouraging rather than discouraging unethical behavior."