Two studies published within days of each other suggest that if you want people to make ethical decisions, corner them in a small office in early morning.

One study by researchers Maryam Kouchaki of Harvard University and Isaac Smith of the University of Utah found that a person’s self-control diminishes as the day wears on, leading more people to give in to the temptation to lie and cheat. Kouchaki and Smith had noticed that self-control lags with severe fatigue, but their experiments on groups of university students and adults found that even a few hours could make a difference.

“Our findings suggest that mere time of day can lead to a systematic failure of good people to act morally,” the researchers wrote in Psychological Science.

The second study, by Andy Yap of MIT’s Sloan School of Management, found that the more space a worker has—the bigger the office, cubicle, desk, and even the chair—the more likely the person is to feel entitled to cross ethical boundaries. Yap told the Harvard Business Review that more space makes people feel more powerful—and more willing to break the rules.

In one experiment, people were deliberately overpaid to see whether they would point out the error. The result: 78% of people in expansive spaces kept the money, while only 38% of those in smaller spaces did. In a second test, when a driver’s seat was increased by one standard deviation above the norm, he or she was more likely to double park, 71% vs. 51%.

Yap told the Harvard Business Review that the larger spaces “allow you to have an expansive posture, and that’s what makes you feel more powerful. And the feelings of power are what alter your behavior.”

Is there a lesson in this? I’m not sure. We need people to be ethical all the time, not just for a few hours in the morning and not just when they’re confined to small spaces. It’s no surprise that our ethical behavior is influenced by a whole range of outside factors; that’s true of all kinds of behavior. Context can make a huge difference. What it means, I think, is that we can never let down our guard. We need to combine a strong sense of right and wrong with constant vigilance.