Believe it or not, some people claim that tricking your brain to sleep only two hours a day is possible without any negative side effects. This works by forcing your brain to enter REM sleep as soon as you start napping. Scientist say that REM sleep is where you start to feel rejuvinated. This sleep cycle infographic can explain it.
Sleeping five times a day for only twenty minutes will trick your brain into thinking you are sleeping longer hours. I’ve read some blogs about it and people say they didn’t have any negative side-effects. (I’ll try to get some more info). In the meantime, you can check out this Polyphasic Sleep Cycle