In the past few weeks, about four or five of my friends decided to try to maximize their productivity for the summer by taking several short naps per day instead of sleeping all at once during the night. Basically this tricks your brain into REM sleep, which is all you really need for your body to feel rested. Dustin Curtis wrote an article about it:

One of the ways to force your brain into REM sleep and skip the other phases is to make it feel exhausted. If you’ve gone 24 hours without sleep, you might notice that you drift away into dreams straight from being awake. This because your body goes instantly into REM sleep as a protection mechanism. The way to hack yourself into entering REM sleep without being exhausted is to trick your body into thinking you’re going to get a tiny amount of sleep. You can train it to enter REM for short periods of time throughout the day in 20-minute naps rather than in one lump at night. This is how polyphasic sleep works.

This entire website is inspiring. Go look!