Sleeping on job improves memory:

Falling asleep on the job for a few minutes can improve your memory and mental performance, according to a team of German researchers. Olaf Lahl at the University of Dusseldorf, Germany, has shown that simply falling asleep does more than refresh the brain-it can improve recall and mental efficiency. In fact, a six-minute nap can have the same effect as night-time sleep on memory. Lahl's team asked students to memorise a list of vocabulary and tested their ability to recall the list after an hour. During the break, some volunteers were allowed to nap for six minutes, while others had to stay awake. The researchers found that those who had been allowed to nap displayed "superior recall" in the memory test compared to those who stayed awake.