If a 15-minute nap during the day = 90 minutes during the night...

[Tavrobel]

I have heard of a method where instead of sleeping at night at all, you just take 5 20-30 minute naps throughout a day, and I have also heard that if you mess up the schedule, you become incredibly tired.

Yeah, the uberman sleep schedule. It'll take about a month to get used to, but theoretically, you could claim about half of the time you spend sleeping at night back. If you sleep too much, even by five minutes, you'll slip from Stage I (REM) into Stage II sleep, where your body is generating all of those drowsiness waves that make you hate life when you wake up (waking up during Stage III or IV will totally smurf you up). The most important thing to know is that more sleep isn't necessarily better, it's the pattern that matters more.

Most people can't handle the uberman sleep schedule.

EDIT: I suck at remembering the actual names of stuff.