Polyphasic sleep
Polyphasic sleep is a term used to describe several alternative sleep patterns intended to reduce sleep time to 26 hours daily in order to achieve a better quality of sleep. This is achieved by spreading out sleep into short naps of around 1530 minutes throughout the day, and in some variants, a core sleep period of a few hours at night.
The process of adapting to a polyphasic schedule can involve a mentally and physically very difficult one- to two-week transition period, especially for the variant known as Uberman sleep. Thereafter, independent testers claim to experience no apparent drop of cognition or alertness, despite the few hours of sleep attained each day. On the other hand, polyphasic sleep typically requires adhering to a rigid schedule, which makes it impractical for many people.
Relatively little scientific research has been performed on polyphasic sleep. Much, if not most, of the information about it comes from the claims of independent testers, many of whom are bloggers.

# Theory
Ordinary "monophasic" sleep consists of several stages, some of which may not be necessary in the amounts or proportions that naturally occur.  Advocates of polyphasic sleep believe that after undergoing controlled sleep deprivation during an initial adjustment period, the brain will start to enter the essential sleep stages much more quickly, as a survival strategy. Once this adaptation is learned, the theory goes, a comfortable and sustainable equilibrium of sleeping in only naps can be established.
Boat racers have used a similar technique to avoid dangers of sleeping for extended periods alone at sea. Astronauts have also occasionally tried similar strategies during extended crises. There is a substantial interest in polyphasic sleep at NASA and among the Military of the United States and Canadian Marine Pilots .

# Practice makes perfect
Current polyphasic users and scientific evidence from Claudio Stampi both suggest that most tiredness dissipates around 10 days into the schedule, and it disappears completely around 14 days into the schedule. However, self-testers often accidentally oversleep while attempting to convert to a polyphasic schedule and consequently fail to fully adapt, or delay their adaptation. Therefore, they remain tired long after the target 14-day end date and many eventually terminate the experiment. It normally takes weeks before your body will adjust to this sleep variant.

# Types
The term "polyphasic sleep" itself refers only to the practice of sleeping multiple times in a 24-hour period (usually, more than two, in contrast to "biphasic sleep") and does not imply any particular schedule.
In application, "Uberman's sleep schedule" is likely to be the most widely known type of polyphasic sleep, and also the most strict. It consists of six naps of 2025 minutes each, occurring four hours apart throughout the day. This is also the closest schedule to the type that has been studied by Claudio Stampi in connection with long-distance solo boat races. Claudio Stampi advocates polyphasic sleep as a means of ensuring optimal performance in situations where extreme sleep deprivation is inevitable (e.g. to improve performance in solo sailboat racers), but Stampi does not advocate the polyphasic sleep as a lifestyle.
"Core sleep" is a variant of Uberman that adds a block of sleep, usually several hours, to the Uberman schedule, replacing one or two naps. (This term is also sometimes used to describe accidental oversleep by someone following Uberman, though one will more likely see the term "crash", and occasionally "reboot".) Another variant is called Everyman sleep schedule.
Buckminster Fuller advocated "Dymaxion Sleep,"   a regimen consisting of 30 minute naps every six hours. A short article was published about this schedule in the October 11, 1943 issue of Time Magazine. According to this article, he followed this schedule for two years, but after that had to quit because "his schedule conflicted with that of his business associates, who insisted on sleeping like other men."

# Criticisms
Some consider the theory behind polyphasic sleep unsound, claiming that there is no brain control mechanism that would make it possible to switch from a typical biphasic (or monophasic) sleep pattern to a "multiple naps" system. They claim, the body will always tend to consolidate sleep into at least one solid block of sleep (usually during the night or early in the morning), and, as a result, adepts of polyphasic sleep suffer through a never-ending period of "adaptation". Critics often point to the fact that there is no scientific evidence, specifically no articles have been published in any peer-reviewed scientific journals supporting the possibility of entrainment of the polyphasic pattern.
Even though scientific polyphasic sleep experiments have shown all cycles of sleep are included in the same percentages during polyphasic sleep, critics have expressed concern that the ways in which polyphasic sleep limits actual sleep time, restricts time spent in peripheral stages of the sleep cycle, and disrupts the circadian rhythm of the body, will eventually cause subjects to suffer the same negative effects as those with most forms of sleep deprivation, such as decreased mental and physical ability, increased stress and anxiety, and a weakened immune system. Polyphasic sleep may also lead to "microsleeps" ("dropping off" or inattention for a few seconds at a time) which may be dangerous when driving or operating machinery. There is a lack of controlled study documenting the negative side effects, but critics point to journals kept by subjects, those who have difficulty waking at specific intervals without oversleeping, as anecdotal evidence that the pattern is unsustainable.
Advocates of polyphasic sleep often claim that the procedure boosts their alertness, but skeptics question whether this alertness is related to the sleep pattern or whether increased epinephrine and cortisol is gained from eagerness to succeed in their polyphasic experiment and their other productive pursuits.  A study published in the Journal of Sleep Research in September of 2002 concerning the effects of napping on productivity found that 10-minute naps tended to improve productivity more than longer naps, which may suggest that the onset of sleep is the cause of the increased alertness.
Polyphasic sleep is also thought to increase REM sleep, but it may also be likely to upregulate slow-wave sleep, causing a polyphasic sleeper to gain less REM sleep in a given period of time than with standard sleep patterns.  Different sleep patterns may also give varied results (former polyphasic sleeper Steve Pavlina reported difficulty switching from Uberman's sleep schedule to Fuller's Dymaxion Sleep schedule).
Most polyphasic sleepers tend to claim that the most difficult aspect of the sleep pattern to overcome is the social aspect, as the work hours of modern careers generally do not allow for the required nap periods at regular intervals.  Personal accounts indicate that missing even one nap can cause heavy drowsiness, and thus even successful polyphasic sleepers often revert to monophasic sleep to accommodate their schedules.

# Alleged Mechanism
According to Claudio Stampi's book ("Why We Nap: Evolution, Chronobiology, and Functions of Polyphasic and Ultrashort Sleep"), in a sleep-deprived condition, measurements of a polyphasic sleeper's memory retention and analytical ability show increases as compared with monophasic sleep and biphasic sleep (but still a decrease of 12% as compared with entrained free running sleep). According to Stampi, the improvement is due to an extraordinary evolutionary predisposition to adopt such a sleep schedule; he hypothesizes this is possibly because polyphasic sleep was the preferred schedule of ancestors of the human race for thousands of years prior to the adoption of the monophasic schedule.
According to EEG measurements collected by Dr. Stampi during a 50 day trial of polyphasic ultrashort sleep with a test subject and published in Why We Nap, the proportion of sleep stages remains roughly the same during both polyphasic and monophasic sleep schedules.  The major differences are (1) the ratio of lighter sleep stages to deeper sleep stages is slightly reduced and (2) sleep stages are often taken out of order or not at all.  For example, some naps may be composed primarily of SWS while REM dominates other naps.
The misconception that polyphasic sleepers experience only REM sleep is still prevalent, perhaps because (1) some theories of sleep suggest that REM is largely responsible for the mental rejuvenation effects of sleep, (2) the original e2 article on Uberman sleep mentions this theory, and (3) many who attempt to adjust to polyphasic sleep have vivid dreams during their naps. It has been documented that depriving rats of REM sleep leads to death in 3 to 8 weeks. REM and non-REM sleep are equally important for healthy sleep. Depressed people are known to experience more REM sleep ; and monoamine oxidase inhibitors nearly completely abolish REM sleep, yet patients who take MAOIs do not exhibit any obvious cognitive deficits (Siegel 2001).

# Attributed polyphasic sleepers
Proponents claim that several famous people applied catnapping to a large extent.
- Leonardo da Vinci - unverified. It seems all that is known about Leonardo's sleep was written after his death. Polyphasic sleep logs claim he slept only 15 minutes at a time, every two hours.  The term "Da Vinci sleep" is often used as a synonym for polyphasic sleep.
- Lord Byron, poet and hedonist.
- Paul Erdos, the itinerant mathematician, slept two hours a day for several decades through a combination of napping and amphetamine use.
- Steve Fossett, while flying non-stop around the world used 5-minute powernaps in regular intervals around the clock.
- Buckminster Fuller claimed to have napped for a half-hour every six hours for two years of his life. 
- Vilna Gaon is said to have practiced polyphasic sleep for most of his adult life, sleeping four 30-minute intervals in 24 hours. He would take three naps throughout the night and one during the day. Introduction to the Gra on Orach Chayim. |first1= missing |last1= in Authors list (help).mw-parser-output cite.citation{font-style:inherit}.mw-parser-output q{quotes:"\"""\"""'""'"}.mw-parser-output code.cs1-code{color:inherit;background:inherit;border:inherit;padding:inherit}.mw-parser-output .cs1-lock-free a{background:url("")no-repeat;background-position:right .1em center}.mw-parser-output .cs1-lock-limited a,.mw-parser-output .cs1-lock-registration a{background:url("")no-repeat;background-position:right .1em center}.mw-parser-output .cs1-lock-subscription a{background:url("")no-repeat;background-position:right .1em center}.mw-parser-output .cs1-subscription,.mw-parser-output .cs1-registration{color:#555}.mw-parser-output .cs1-subscription span,.mw-parser-output .cs1-registration span{border-bottom:1px dotted;cursor:help}.mw-parser-output .cs1-hidden-error{display:none;font-size:100%}.mw-parser-output .cs1-visible-error{display:none;font-size:100%}.mw-parser-output .cs1-subscription,.mw-parser-output .cs1-registration,.mw-parser-output .cs1-format{font-size:95%}.mw-parser-output .cs1-kern-left,.mw-parser-output .cs1-kern-wl-left{padding-left:0.2em}.mw-parser-output .cs1-kern-right,.mw-parser-output .cs1-kern-wl-right{padding-right:0.2em}
- Ellen McArthur, while sailing around the world used 310-minute catnaps frequently around the clock.
- Sir Hubert Opperman and thousands of other practitioners of the form of long-distance endurance cycling known as randonneuring have successfully completed events that required them to propel themselves over 1,200 km in less than 90 hours, under rules that effectively proscribed sleeping more than a few hours at a time. Many in fact sleep less than 30 minutes at a time over the challenging routes, the best-known of which is Paris-Brest-Paris, a 1,200-km challenge that attracts 3,000+ riders from over 20 countries every 4 years.
- P. Diddy - unverified. He spoke about sleeping habits similar to polyphasic sleep patterns on the show "MTV Diary," claiming that he sleeps between two to four hours a day by taking small accumulative naps. It has been known that his sleep schedule is more of a practicality than a choice in order to conform with his busy lifestyle.

# Urban legends
Popular myth has labeled some icons as polyphasic sleepers:
- Benjamin Franklin  It is Franklin who said "There will be sleeping enough in the grave" as well as "The sleeping fox catches no poultry". However, he is also attributed with "Early to bed and early to rise makes a man healthy, wealthy, and wise", which is a definite monophasic mantra.
- Thomas Edison  Edison is known to have held sleep in contempt. He also practiced catnapping. Yet his naps, often on the floor, could take several hours. He had a napping cot in his office. Most importantly, however, he would take a normal 4-5 hours sleep in the night. Due to his contempt for sleep, he would often claim to sleep less than it was actually observed by his co-workers. He often worked throughout the night. However, he would usually sleep through most of the next day. During a short period of life, Edison kept a diary whose scanned versions are available on-line.Template:Facts The diary shows that he would often wake up at 56 a.m. and linger in bed till 89 a.m. repeatedly waking up and falling asleep again. He was definitely not a polyphasic sleeper despite a widely spread urban myth.
- Thomas Jefferson  This claim is likely to be an urban legend as Jefferson, in his own words, indicated that he slept irregularly in a single block of 58 hours in the night, always after 3060 minutes of inspirational reading (Letters to Vine Utley, 1819).
- Napoleon  Though the demands of leadership of an emperor may well have resulted in sleepless nights, no documents have been found to uphold a strategic schedule of polyphasic sleep.
- Nikola Tesla  Rather than being polyphasic, Tesla used to work excitedly for extended periods of time seemingly without fatigue (even above 70 hours). However, he has also been reported to sleep through the entire day. This would be an anti-polyphasic routine, which may be useful for following certain trains of thought and analysis.
- Albert Einstein - Einstein enjoyed occasional super-bouts of 9 hour sleep and was generally a long sleeper.
- Frank Lloyd Wright -- In tours of his home and studio, "Taliesin", in Spring Green, Wisconsin, tour guides point out his small bedroom nook, located within easy access of his studio. The guides claimed that Mrs. Wright insisted that he build himslf a separate bedroom because his 2 - 3 hour sleep periods interfered with her sleeping.  The guide said Wright took frequent naps throughout the day, as well.

# Polyphasic sleep in fiction
- Polyphasic sleep was also popularized on Seinfeld, when the character Kramer attempted to adapt to "Da Vinci's sleep pattern" in The Friars Club episode.
- Some writers have depicted Batman as sleeping only two hours every twenty four hours; the exact schedule has not been shown. In other instances Batman is mentioned to have stayed awake for up to three days straight.
- The character Shellman (Skalman) in Bamse is a polyphasic sleeper; using a special alarm clock as a reminder when to sleep and when to eat.
- In Ursula K. Le Guin's story The Word for World is Forest is set on a planet where the monkey-like hominids that make up the native population practice polyphasic sleeping naturally, finding alternative methods of sleep strange.  Later, one human character attempts, with some success, to imitate the native sleep patterns.
- In Farley Mowat's novel Never Cry Wolf the main character takes what he calls "wolf naps," a schedule that appears to be much like polyphasic sleeping, though no schedule seems present.