That Devil on Your Shoulder Likes to Sleep In

It is often asked why good people do bad things. Perhaps the question should be when.

More likely, it’s in the afternoon or evening. Much less so in the morning.

That’s the finding of research, published in the journal Psychological Science, which concludes that a person’s ability to self-regulate declines as the day wears on, increasing the likelihood of cheating, lying or committing fraud.

This so-called morning morality effect results from “cognitive tiredness,” said Isaac H. Smith, an assistant professor at the Johnson Graduate School of Management at Cornell University and co-author of the article withMaryam Kouchaki, an assistant professor at the Kellogg School of Management at Northwestern. “To the extent that you’re cognitively tired,” Dr. Smith added, “you’re more likely to give in to the devil on your shoulder.”

Link