Maybe you’ve had trouble focusing on your work after tossing and turning the night before, or you’ve found yourself making silly mistakes. But one expert who has studied the link between sleep deprivation and ethical behavior on the job found some even more troubling outcomes, like more cheating.

Christopher Barnes, a professor at the University of Washington’s Foster School of Business, recently shared some of his research with the HBR blog. He says it spring boarded from scientific research that indicates lack of sleep drains glucose form the pre-frontal cortex, an area of the brain that regulates self-control.

Barnes and his team decided to investigate how sleep deprivation and a corresponding lack of self-control might impact ethical decision making in the workplace. They conducted various studies, on the job and with clinical test groups, and found that even a small amount of sleep loss can make a difference in a person’s choices.  In one study there was only a difference of about 22 minutes of sleep between those who cheated on a trivia test and those who didn’t.

Barnes says it’s troubling that managers, who are making some of the most important decisions in the workplace, are often more sleep deprived than the average American worker. You can read more about his findings on HBR Blog Network.