Most people only think that there is one way to sleep: Go to sleep at night for 6-8 hours, wake up in the morning, stay awake for 16-18 hours and then repeat. Actually, that is called amonophasic sleep cycle, which is only 1 of 5 major sleep cycles that have been used successfully throughout history. The other 4 are considered polyphasic sleep cycles due to the multiple number of naps they require each day. How is this possible? How is this healthy? Well the most important of every sleep cycle is the Stage 4 REM (Rapid Eye Movement)sleep, which has been shown to provide the benefits of sleep to the brain above all other stages of sleep. When changing over to a polyphasic cycle, the lack of sleep tricks the body into entering REM sleep immediately instead of 45 to 75 minutes into sleep like in the monophasic sleep. This way, you still get the benefits of 8 hours of sleep without wasting all of the time it takes to get to REM cycles, resulting in a much more efficient sleep cycle. Here are polyphasic cycles:
Uberman Cycle:
20 to 30 minute naps every 4 hours, resulting in 6 naps each day. The uberman cycle is highly efficient, and usually results in feeling healthy,  feeling refreshed upon waking and extremely vivid dreams. Many uberman-users report increased ability to lucid dream as well. However, the rigid schedule makes it near impossible to miss naps without feeling horribly tired. Blogger Steve Pavlina tried the cycle for 5.5 months and had amazingly positive results.He only reverted to monophasic sleep so that he could be on the same cycle as his wife and children. Read his articles and updates on the cycle here.
Everyman Cycle:
One longer “core” nap that is supplemented with several 20-30 minute naps. The most successful variations that I have read...