For every hour that sleep was interrupted the previous night, research participants monitored during a 42-minute task spent an additional 8.4 minutes cyberloafing—checking personal e-mail or visiting unrelated websites—according to a team led by David T. Wagner, of Singapore Management University. The fact that sleep-deprived people are more apt to give in to cyberloafing temptation can also be seen on the first Monday after the switch to daylight saving time, when Google users search for 3.1% to 6.4% more entertainment-related websites than on other Mondays, the researchers say.

A version of this article appeared in the April 2013 issue of Harvard Business Review.