Air traffic controllers worked three simulated day shifts from 7 a.m. to 3 p.m. and then returned after an eight-hour break for an 11 p.m. to 7 a.m. night shift. Compared to a no-nap control group, controllers who napped from 3:00 to 3:45 a.m. performed better on a vigilance test and an air traffic simulation test, and reported feeling less sleepy.

Researcher Pamela Della Rocco says naps could be useful as a countermeasure to performance fall-off and sleepiness on the midnight shift.