The Effect of Brief Naps on Alertness and Cognitive Performance
If you don’t get enough sleep at night, a quick 10 minute nap may help improve your alertness and cognitive performance. However, shortening it to a 30 or 90 second nap won’t cut it.
Psychology researchers performed a study with 16 subjects, each restricted to 5 hours of sleep at night. The subjects were split into 4 groups — no nap, 30-s nap, 90-s nap, and 10-min nap. Subjects that took naps for 90 seconds or less were not found to perform any better on alertness and cognitive tasks. However, subjects that took a 10 minute nap significantly improve performance in multiple post-nap tests. This seems to suggest that only stage 2 sleep helps you recuperate from lack of nocturnal sleep.
Tietzel, A. J. & Lack, L. C. (2002). The recuperative value of brief and ultra-brief naps on alertness and cognitive performance. Journal of Sleep Research, 11, 213-218. [PDF]