The study: Colorado College professor Kristi Erdal and psychology student Christina Draganich tricked subjects into believing that the quality of their previous night’s sleep could be determined by measuring their brain waves. Those randomly selected to be told that they’d had a below-average percentage of REM sleep significantly underperformed on an auditory math test, regardless of how they had actually slept—mirroring the effects of real sleep deprivation.
A version of this article appeared in the September 2014 issue of Harvard Business Review.