I've written before about the importance of sleep.

Tired brains lose their capacity to think critically, to evaluate data, and to understand the meaning of evidence. But chronic fatigue in the workplace isn't the only invisible risk we run daily. So too is speed.

I know, I know: We're all supposed to run fast companies in which quick decisions today are better than perfect answers a week from now. In the blink of an eye, we're all supposed to be naturally brilliant. But I'm not so sure.

Recent experiments conducted by the Kellogg School's J. Keith Murnighan demonstrated that, asked to choose between two communications—one honest, the other less so—the students who were given more time made the more ethical choice. Those under time pressure were more selfish. But given the opportunity for contemplation, participants were able to consider the consequences of their actions and to think of others beyond just themselves.

I can't be surprised by these findings. Ethical thinking is cognitively expensive: it takes effort, focus, and time. It's easily crowded out by multitasking, distractions, and fatigue. Many other experiments demonstrate that people often make unethical choices not because they intended to—but because they didn't see that ethics were involved at all. To understand the full repercussions of any decision takes time and attention. It can't be done if the text you're sent with a tricky question requires an instant solution. And it won't be done if all you're trying to do is whittle down to a manageable number the screen full of emails you received during lunch. Time and focus are both hard to get and to hang onto in a busy workplace.

Reading the study, I can't help but remember a great detail I found when I ploughed through the documentary evidence presented in the trial of Enron CEO, Ken Lay. The company Post-it notes carried a Martin Luther King, Jr. quote: "Our lives begin to end the day we become silent about the things that matter." But of course the company moved so fast, no one ever had time to read it—never mind think about it.