Polyphasic Sleep: 5 Years Later!

Contents

IntroductionWhat changed in 5 years?Impact of the original articlePolyphasic WomenWhy don't I try and see for myself?Sleep deprivation vs. alcohol abuseFree-running sleep cannot be compared to overeatingScientific challengeWhat is my agenda?Can battling polyphasic sleep hurt SuperMemo?What are my future research plans into polyphasic sleep?Are polyphasic sleepers dumb?Could polyphasic sleep work for mutants?BBC experimentClaudio StampiSteve PavlinaPuredoxykLinksChronobiology

Polyphasic sleep adaptation mythsCircadian timing of napsSome chronobiological findings from SleepChart and SuperMemo relevantto polyphasic sleepChronobiology vs. SleepChart

Biphasic sleepMonophasic sleepPreference for night sleep

Polyphasic sleep vs. SleepChartPolyphasic sleep (Stampi yachting research)Uberman sleep attempt

Uberman sleep logsTwo-process sleep model vs. polyphasic sleepPolyphasic rollercoaster

Polyphasic sleep attemptPhase response curve (PRC)Polyphasic sleep rPRCSleep block length distribution

Conclusions

Links

Since the publishing of my original article on "polyphasic sleep", I received a lot of mailwith requests to produce an update, esp. on conclusions coming from my contactswith young people attempting to implement a polyphasic sleep schedule. Quite a bithas changed in those five years, and those who would like to sleep polyphasically gotfar more opportunity and material to research the subject thoroughly and make rightdecisions. In this followup article, I would like to address the criticism of the originalarticle, and write a few words about how the new tools made available in SuperMemohelp study sleep and predicate on the possibility of sleeping polyphasically.

Introduction

What changed in 5 years?

The present article is justified by a couple of changes that occurred in the last 5 years.Here are a few important contributors to my knowledge of the polyphasic world:

I received some 500 pieces of mail and got in personal touch with manypolyphasic adepts. Of those attempts that I was given a chance to monitor, allwere unsuccessful. Some of the critics of the original article claimed that they dosleep polyphasically, but I received no data that could serve as the basis forverification. The most interesting conclusion coming from the mass of mailreceived is that people drift towards polyphasic sleep less as a result of theirhunger for achievement, and more for their prior problems with sleep. They oftenthink of polyphasic sleep as a panacea for all their sleep problems. Thisperception is magnified by multiple blog claims.I received a couple of SleepChart data submissions demonstrating how difficultthe struggle with the polyphasic sleep is. Admittedly, I was quite impressed withthe degree of determination some of those experimenters showed.YouTube entered the scene and now anyone can see individual tribulations,black-ringed eyes, dishevelled hair, mumbling voices, and the plain torture oftrying to stay awake. As always, there are always those who beam health, smilesand the declarations like "I now feel better than ever". Below I include a lovelyexample of a YouTube contribution; well done, cocky, honest, representative,funny, and iced with a positive ending:

Also the famous Stampi experiment with Francesco Jost is now presented in thisdocumentary:

The newest version of SleepChart makes it possible to model the changes insleep propensity. Even though the model applies to free running sleep, itsapplication to polyphasic sleep provides a good illustration of the roots ofpolyphasic suffering.Some of polyphasic mythology seems to have died out. No longer do we hearmuch of Churchill or Jefferson sleeping polyphasically.

Impact of the original article

Overall, I consider the original article a success. When young men turned to me with arequest to help supervise their experiments, I had to start from trying to dissuade themfrom the idea. I expected many refusals to be met with "No. I will still try. I need moretime per day", but I got surprisingly many "I got sleep problems. If free running sleepmight help, I will try it first. Sounds sensible". As I wrote previously, those are"rebellious men ready to seek new ways for maximum productivity". No scientificargument can be persuasive in such cases. After all, all reasoning can easily bequashed with "science does not have all the answers yet". None of the young rebelssucceeded in entraining polyphasic sleep, yet some were persistent enough to providesome SleepChart data that sheds some more light on the implausibility of thepolyphasic sleep schedule. This data can now be compared with sleep habits of youngstudents who use SleepChart to better understand their own circadian cycle.The mail that I have received was mostly critical, but it should not be used as ameasure of success. It is not important what proportion of readers would agree withme. It is important how many gave up the idea of sleeping polyphasically as a result.

Within the five hundred pieces of mail, I roughly estimate the distribution of theirnature as follows:

50% - criticism of the article from the adepts of polyphasic sleep40% - requests for help in implementing polyphasic sleep with the help of toolslike SleepChart, etc.10% - grateful mail of the sort "thank you for saving me lots of time and health. Iwanted to try polyphasic sleep but, after reading the article, decided not to"

10% may seem like a very low conversion rate. However, this translates to hundreds ofhours of someone's time. I am sure it also translates to some health benefit. Forexample, a great deal of polyphasic attempts end up with a cold or influenza, whichmust reflect the impact of this sleep schedule on the immune system.

What Aaron wrote is pretty representative of the 10% group: "The idea of sleeping innaps spread throughout the day intrigued me, as I have always suffered from what Iwas unable to properly quantify, but now know is DSPS. If I do not use an alarm clock,and go to sleep when I become tired, I see my sleep/wake times shift to significantlylater times every day (hours later). This has been a constant source of frustration forme, and I considered a polyphasic schedule in order to help correct the problem.However, after reading "Polyphasic Sleep: Facts and Myths", I have decided this wouldbe a sincere waste of my time".

More frequently, I was a bit less successful. For example, Joel wrote: "I am writing toask for your guidance on my attempt at the "Uberman" sleeping schedule - wherebyone sleeps 20 minutes at 6 evenly spaced times during a 24 hour period. I have readyour arguments against polyphasic sleeping, but I'm set on attempting it. Your plea forpeople to contact you if they are considering it is what motivates me to email you nowas I'm interested in my potential discomfort being beneficial to sleep research. I'd liketo volunteer to log my attempt with your sleep chart software and answer anyquestions you have about my experience".

Criticism would usually skirt around the science argument and quote from blogs ofpeople who claim they have succeeded with polyphasic sleep. For example Kop wrote:"There are MANY people who successfully adapted. [...] You simply neglected to citethem, and you cited only people who failed. I think this is very unfair and misleading toyour readers. I may sound like a broken record, but even if you believe that everyonewho claims to have been successful is lying you should let your readers make thischoice and you should definitely not just completely leave out all the information youpersonally don't agree with".

At the extreme end of the range, there was mail from George who straightforwardly

accused me of lying: "It is important to realize that most of the experimenters areAmericans, because apparently you don't understand the dynamics of our culture.Briefly put, you paraded evidence that seemed to support your claims, whilecompletely ignoring evidence that does not. For example, you flatly state that nopolyphaser is ever a woman, while at the same time quoting from a blog written byone! (A search at YouTube.com will reveal other female polyphasic sleepers.) Inanother instance, you quoted a medical disclaimer from one polyphasic, while leavingout his comments on the experiment's great success. This practice on your part,Doctor, is seen by Americans as being dishonest. Dishonesty by a scientist completelyruins credibility. Since it's easy to believe that you were dishonest on polyphasic sleep,it's also easy to believe that you are lying about your product, SuperMemo. This isgoing to cost you money, Doctor. Who is going to buy a product by a lying scientist?

Most importantly, polyphasic sleep mania did not grow exponentially as I feared. Itreached some plateau and its population includes fewer true experimenters and morezany characters that won't be persuaded by any means except their own perpetualfailure. I am then proud that my voice is relatively loud among the few who spokeagainst the practise. Sleep researchers are too busy to study freak ideas. Doctors donot perceive it as a danger as they are pretty unlikely to meet an actual victim. Youneed the magnifying glass of the net to see the worldwide size of the phenomenon.Thus efforts of a goodwilled activists grow in relative importance.

Polyphasic women

My greatest mistake committed when writing the original article was to inadvertentlyuse the word "invariably" instead of "predominantly". As a result, it seems like half ofthe critical mail accused me of distorting facts by claiming that there are no womenwho tried to sleep polyphasically. Some even went as fast as to claim I discredit ordisparage women!? For starters, if this was to be a lie, it was a pretty lame one, I evenquoted from polyphasic blogs written by ladies. There is nothing to stir people'saggression like a lame lie, and if I committed one, I would have to be tossed into thedumbest liars category. Secondly, should my claim not rather be interpreted as "Ladiesare too smart for this. Only guys start wars and apply crazy sleep schedules".Retroactively, I corrected the unfortunate word at the risk of getting fewer inspiringpieces of mail from the less tolerant or the less inquisitive range in the readerspectrum. Ah yes, just in case, I did not spell it clearly enough: there are women whothink sleeping polyphasically is a good idea!

Why don't I try and see for myself?

Very often I am being asked how I can claim any authority on polyphasic sleep withoutever trying it myself. For starters, I do not claim to be a polyphasic sleep expert. As a

humble biologist, I simply need to recall the ABC of chronobiology to figure out thatpolyphasic sleep is not feasible. You do not need to be a junkie to study drugaddiction, even though a glass of vodka might be a recommended one-time treatmentto an abstinent investigator of alcoholism. I understand the pain of the alarm clockbecause I used it sparingly during my university years as well. I understand the pain ofjet lag and sleep deprivation from my early turbulent years of involvement in theSuperMemo business. However, I need a fresh brain for my work. Even one day of ahazy mind is a loss. I cannot possibly hope to struggle through a polyphasic routine inhope of proving that the elusive and ever remote "adaptation" is just an urban myth. Ifsomeone told you to lie on the railway tracks with a promise of being struck by nirvana,you would refuse. For you know with sufficient probability that the outcome wouldmore likely be pretty gory.

Sleep deprivation vs. alcohol abuse

Sleep researchers love to compare sleep deprivation to intoxication: both disrupt one'sself-assessment abilities. Like an alcoholic who always claims "I am not drunk. I am justinebriated", a sleep deprived person will often say "I am fine. I am crisp and alert", whilehis or her ability to perform mental tasks may be seriously impaired. Driving whensleep deprived may be as dangerous as driving while intoxicated. This loss of self-assessment capacity may in part explain why so many polyphasic bloggers tend toclaim they have adapted. They tend to write about their success at the moment oflucidity or euphoria (see the chronobiology insert on how this can be explained withthe two-process model of sleep), while ignoring those brain dead moments as"temporary setbacks", transitory adaptation state, etc. In those hazy moments, ablogger may be unwilling to update the blog, magnifying the bias as perceived from theoutside. Adaptation to polyphasic schedule is not possible, but this self-assessmenthandicap is just one of many reasons that boastful bloggers need not be branded asliars on the sole basis of their claims. Perhaps it is even possible to flatten ordesynchronize the circadian function bad enough to lessen the average pain. Needlessto say, with all genetic cascades resting on the circadian cycle, such an outcome canonly lead to a health disaster. It could be likened to applying contradictory stimuli tothe gut in order to prevent the natural progression of peristalsis. What a polyphasicsleep adept is risking at such point is an outcome comparable with the fate of MrCreasote in the "Monty Python's The Meaning of Life" (see on YouTube - very drastic!)

Free-running sleep cannot be compared to overeating

One of the most persistent myths about sleep is that our body is programmed to get asmuch sleep as possible. Even some reputable researchers subscribed to this idea!They compare sleep to overeating. Some note how long Inuit sleep in winter. Othersnote that people allowed to sleep freely often binge heavily clocking up an indecent

number of sleep hours. As if conservation of energy was the main function of sleep. Asif all animals were made as lazy as they are perpetually hungry. However, few candemonstrate any evolutionary or biological advantage to getting more sleep thanneurally necessary. This harmful myth might make you think that free-running sleepwill make you sleep longer in the same way as free access to the kitchen will make youovereat. Considering the known functions of sleep, there is no specific benefit tosleeping beyond the standard 6-8 hours. Sleep is a physiological consumer of benefitsaccumulated in waking (such as learning, exercise, etc.). Its healthy homeostaticregulation roughly ensures the optimum proportion of sleep to waking. People whobinge on sleep in free-running conditions, usually come from a period of long-lastingsleep deprivation. Their sleeping time quickly drops to their natural average after acouple of days of the free schedule. If your main concern is time, you can survive onless sleep and get more time at the cost of your mental acuity. If your main concern isthe brain power, you should live by the motto: Maximum efficiency of sleep isaccomplished when sleeping without artificial sleep regulation (i.e. without alarmclocks, pills, designer schedules, etc.). Free-running sleep schedule will make yousleep less on average. It will make you sleep much less than on those days of anyartificial sleep schedule that forces you to catch up with the accumulated sleep debt.Irregular schedule is bound to produce deficits because you can accomplish irregularsleep only by interfering with it.

Scientific challenge

With all the mail criticising my polyphasic sleep article, not a single one!, came againstthe basic scientific premise, which was supposed to make the core of my argument. Ireceived some mail that quoted from scientific literature or from Dr Stampi's book.However, again, not a single one! came against the basic scientific premise (see theyellow inset below). To make the article readable, I mixed science with humor and adegree of provocation. My experience says that the importance of the message doesnot correlate with the degree of article's popularity. I never get any comments on "Twocomponent model of memory". It does not affect anyone's emotion. It reads like dryscience. We got very few reprint requests back at the day of publication (beforeplacing the article on the web). And yet it might be one of the most importantcontributions of SuperMemo to understanding memory. This is why when writing thepolyphasic sleep article, I chose a more provocative style to address the youngeraudience. Understandably, most of the criticism focused then on the "readable"portion (despite a large disclaimer that it should be taken with a grain of salt). As such,all criticism missed the main point of the article (!) and did not contribute much tothe discourse. Here is a chance for the critics again to address the central point:

Human sleep patterns reflect the underlying circadian rhythm whose period is roughlyequal to 24 hours. This circadian cycle calls for a major sleep block every 24 hours. The

body clock can be entrained with phase shifts of up to 3 hours. However, the circadianlows cannot be partitioned. The timing of the main low cannot be positioned in any otherway than by a phase shift. Periodicity cannot be eliminated without a detriment tohealth. Circadian components underlie the structure of sleep that is essential for itsfunction. Therefore, in individuals with healthy regulatory sleep system, no sleepschedule can skip the main period of the consolidated subjective night sleep.

In practise this means that only mono- and bi-phasic sleep patterns are healthy andrecommended. Note that the mono- vs. bi-phasic choice will depend on the circadianwave function, which has two minima in a 24 hour period, only one of which has beenproven essential for the correct function of sleep (until now). Polyphasic entrainment isjust a pipe dream. So is the even more extreme hope of sleep on demand. Please donot send me mail with Eureka exclamations that there are polyphasic women in thisworld, or that my blog selection is biased (because it is!). Unless you can provideevidence against the core argument in yellow above, our exchange is likely to bepointless.

What is my agenda?

Lots of critical mail mentioned my "hidden agenda". Ever since I wondered what myhidden agenda might be. Standard ulterior "agendas" revolve around money, feelingimportant, or a ticket to fame. The article is free, and earns me no money. It hardlymentions SuperMemo, so it does not serve as a promotion article. It earns me no fame.How about feeling important then? The article had some success in preventing somepeople from plunging into a polyphasic waste of time. Therefore I do consider thearticle important. Yet at 50% criticism rate, I would rather need to don a mantle of thickskin even though I am rather of fabric that loves loony criticism. The more awkwardand preposterous the accusation, the more fun it is to combat it. Perhaps thismechanism breeds people who like to rub others the wrong way. Yet, if all I wanted todo is to be contrary, I could employ more aggressive and unkind tools of derision. Iopted for the opposite: due respect to those young people who experiment with theirhealth. I combined that respect with a bit of harmless fun poking for the sake of justmaking the article a bit more effective in addressing the emotion of the reader.In addition to the original agenda behind the article, you may think that after 5 years, anew agenda might be emerging: it would not be nice to eat crow! Most of people hateto admit their mistake. However, this is less of a problem in science, where eachopportunity to change one's mind is always associated with learning something new.True hard-core scientists love to find out they were wrong because they equate it witha major step to getting closer to revealing the truth. I am not too emotional aboutpersonal accomplishments or being always right. I would also rather welcome the needto admit being wrong because it could only be a result of some major scientificdiscovery. It would certainly require an update to our models of sleep. This would meanthat we would better understand the mechanisms of sleep, and new knowledge always

opens new vistas, esp. for my true core agenda: striving at faster and better learning!Unfortunately, the probability of such earth-shattering discoveries is not much greaterthan a chance that humans will soon find a way to squeeze through a wormhole. Someone suggested that my agenda is "free running sleep". This is hard tounderstand. I do adhere to free running sleep religiously. I do tell people of itsblessings (and inconveniences). However, other's people polyphasic sleep does notinterfere with my free running sleep lifestyle. It does not detract from its value. It doesnot hurt me or shame me. Why would this be my agenda?

My true and only agenda behind writing the article was to stop young men from doingstupid things to their health. In the belief that polyphasic sleep is not feasible, I have noagenda: it is just a fact that needs to be told to some people.

Can battling polyphasic sleep hurt SuperMemo?

Someone warned me that a foray into a pseudoscientific field, as well as battlingsuperstitions with sarcasm or derision may undermine the stricter and more scientificfeel of supermemo.com. This prediction seems to be wrong. Polyphasic sleep andSuperMemo audiences are largely separate. Most of people get to SuperMemo whenthey discover it when searching for efficient ways of learning. They already have astrong intuition that they need something like SuperMemo, and only need to find theright tool for their goals. They hardly ever decide upon it having read lengthy articles.And in those rare cases, they are predominantly encouraged. This probably comesfrom the fact that only one kind of people read supermemo.com: those who likescience. No one with a true love for science can go pass by SuperMemo indifferent.The polyphasic article clearly warns when it moves from fact to humor (and intentionalbias). I see no evidence it has hurt SuperMemo in any way. At the same time, I gotsome mail indicating that people who originally searched for polyphasic sleep articlesbecame interested in SuperMemo. All in all, the article does not seem to have muchimpact on SuperMemo, and whatever impact it has, it is probably positive. Most ofangry mail came from worshipers of polyphasic sleep, none of who, admitted everusing SuperMemo. No wonder. They are rarely of the science-loving type.

What are my future research plans into polyphasic sleep?

Some readers concluded that I might be a researcher who studies polyphasic sleep fora living. No! I took on the subject only as a short-term assignment. I study the impactof sleep on memory and learning. Even though all extreme angles taken to any subjectin science are always a provocative source of inspiration, in the light of my interest inlearning, polyphasic sleep emerges as an extremely dangerous lifestyle formula.Luckily, it is not sustainable enough to do much damage, however, it also helpsperpetuate lots of catchy myths that may affect how young people approach sleep and

health in general. Polyphasic sleep is not a neat study subject. Scientists like simplicity.They construct simple research models to make it easier to arrive at valid conclusions.I love free running sleep concept as a research model. It speaks of unadulteratednatural healthy sleep. Polyphasic sleep was invented for unnatural survival situations,and its Uberman variant is a widely mutated invention of teenagers who hope to savetime on sleep or solve their sleep problems. Choosing a polyphasic sleep as a model,would be like choosing a multiplanet system to test Newton/Keppler's laws, while atwo-planet system would do as well and produce results eons earlier. Instead ofcomplex Fourier analysis, we have simple and clear formulas that tell the entire story.

Are polyphasic sleepers dumb?

Someone accused me of using derision and painting polyphasic sleepers as dumbindividuals who cannot figure out that polyphasic sleep is impossible and comparisonswith da Vinci and Edison are simple myths and Internet rumors. This accusation canonly come from inattentive or selective reading. Let me requote: Even though it is notnice to poke fun at anyone, I hope I do it for the right cause. After all, ignorance andmental flops happen to everyone, incl. the greatest geniuses of history. Those youngmen show many characteristics that will make them successful in life: perseverance,curiosity, willingness to experiment through pain, voracious attitude, zeal for actionand change, etc. Many of those quoted bloggers will go on to do great things in life.Naturally, I do not believe that will happen on a polyphasic sleep schedule.Nevertheless, with all the extra information available on the net today, it is true that it isless justifiable for a reasonable person to take on polyphasic sleep today than it was 5years go. Polyphasic sleepers today are not dumb. However, they are at least veryunscientific. They may also often be pretty narcissistic or downright arrogant. Thosecharacteristics do not help clear reasoning either.

Could polyphasic sleep work for mutants?

Is it possible that there are individual who can actually adapt to the polyphasic sleepdespite its infeasibility for the majority of the population? This is possible, but highlyunlikely.I raised that possibility less for its probability, and more for the sake ofsoftening the accusation that those who claim polyphasic sleep feats are liars. To make"mutant theory" workable, we would need a series of mutations that would producesleep without a circadian component. Or a mutation that would allow of homeostaticgeneration of circadian states that periodically occur in the brains of all vertebrates. Itis as hard as to imagine a mutation that would allow of defecating in 25g portions. Or amutation allowing of asynchronous voluntary peristalsis. Or a mutation that wouldreplace a blinking reflex with two separate independent regulatory blinkingmechanisms for both eyes. Or a perpetual syncopated heart rhythm with alternating3:6:3:9:3:6 interval ratios. Or a separate contraction of atria, or separate repolarization

of ventricles, etc. Or a menstrual cycle that can be entrained to shift-work withbleeding every 9 days. Why do not people try those "physiological manipulations"?Actually they do. But it takes a hard-core looney to try to prove that "sleep is notnecessary" or even "food is not necessary and can be substituted with meditation".The closest disorder that can match the hypothesis that polyphasic sleep might beenabled by a mutation is narcolepsy, in which individuals node off many times duringthe day indeed. However, this is a homeostatic disorder that does not flatten thecircadian function. As such, narcoleptics sleep more than healthy people, not less.

BBC experiment

I was delighted when the BBC turned to me to assist in designing an experiment inwhich a BBC presenter would attempt polyphasic sleep. However, program's limitationsmade it impossible to run the experiment on the proposed scientific basis with asupervision of a sleep lab. Nevertheless, the final outcome turned out pretty hilarious.The guinea pig volunteer turned out to be no one else than Bill Turnbull! The programultimately aired in 2006 on BBC One's The One Show. Bill would present the Breakfastduring the experiment, and the audience had an opportunity to see the impact of theexperiment on his sleep-deprived performance. Unfortunately, the show did not makeit to YouTube for your enjoyment.

Claudio Stampi

Some of the criticism came from people who read Claudio Stampi's book Why We Nap.My article was accused of trying to contradict or undermine the contribution of areputable sleep researcher. It is true that with the advantage of two extra decades ofresearch, I disagree with some of Stampi's original hypotheses. Largely so doesStampi. Let me then unequivocally express my admiration for Stampi's passionateresearch and meticulous analysis of human reaction to drastic changes in the sleepschedule. His research can definitely be considered as pioneering work in the study ofthe extremes of chronobiology. For those who still believe that Stampi advocatespolyphasic sleep as a lifestyle, an ancient quote from his book should clear things up:"the author would like to caution against misleading interpretations of theseconclusions. What is being proposed here is not that polyphasic sleep is preferable tomonophasic sleep, nor that everyone should now switch to a multiple napping behavior"panacea." It appears obvious that quasi-monophasic sleep monophasic sleep plusoccasional naps is what comes most naturally to the majority of adult humans and afew other species. If somewhere in evolution such species have developed the abilityto sustain wakefulness for relatively prolonged periods, most likely this ability occurredin response to some sort of important and advantageous adaptive pressure".It is important to note here that Dr Stampi could identify only a modest decline incognitive function during his polyphasic sleep experiments. This may stand in seeming

contradiction with other research or with simple circadian measurements of memoryperformance (as in the circadian graph picture). Including a circadian component inmeasurements yields siginificant cognitive differences in the course of a normalundeprived waking day. The tests Stampi chose to measure cognitive performanceskirt around the essential question as to the primary long-term neurophysiologicalfunction of optimally timed REM-NREM interplay in sleep (in Stampi experiement withFrancesco Jost, REM and NREM rarely occurred together). If the hypothesized memorystorage optimization function is considered, it is impossible to verify the status ofmemory with short-term tests as, in theory, the network function of the brain taken asa black box should remain unchanged. The neglect of sleep structure would show onlyas a cumulative long-term inability of the brain to build up new skills and reasoningpowers. Secondly, the creative potential of an optimized storage is also difficult tomeasure, and will definitely show a cumulative effect requiring a long-term study. Lastbut not least, lack of the circadian effect can only testify to an insufficient sensitivityand/or timing of the tests chosen. Even if the homeostatic component of alertnessensures that we can seemingly focus on simple mental tasks and perform them prettywell (e.g. memory tasks, driving, simple calculations, etc.), the circadian low will affectthe ability to sustain a mental effort or undermine its creative aspect. Tests that aresufficient for Dr Stampi's goals (e.g. maximizing alertness in a solo yachting race)cannot be used to make claims about the long-term impact of polyphasic sleep as alifestyle. One polyphasic adept asked me: "I want my doctor to supervise myexperiment. What parameters, do you think, he should track?". It is not much differentthan asking: "What tests I could do to check if smoking is safe? What tests can help mesee the impact of smoking on health?". We all know that smoking or shift-work do notcause a significant impairment in a short term. In the long run though they both cankill.

It should also be noted here that even in serious sleep medicine literature there is aconfusion between the homeostatic and circadian sleep components. Very often,researchers fail to differentiate between the two when investigating impact ofenvironmental factors on sleep. We all know that coffee can help one survive a sleepymoment. It is important to ask though if its effects are homeostatic or circadian. Cancoffee dispel sleep inertia? Can it help overcome circadian lows? It is not enough to saythat coffee helps overcome sleepiness if its impact on the circadian sleepiness isnegligible. Everyone who is familiar with the jet lag can testify that the foggy brainstate does not evidently deprive one of one's basic mental skills, and yet it can entirelyruin one's productivity by affecting self control, creativity, motivation, and more. This iswhy globe-trotting politicians are a poor material for groundbreaking peace or tradedeals, even if they believe they can function well on 3 hours of sleep or in a jetlaggedcondition. Dr Stampi's findings, highly applicable to emergency situations, should notbe used to diminish the importance of well-timed natural sleep for the function of the

brain, and the fact that artificial designer sleep schedules are very harmful.

Steve Pavlina

In my article I wrote: Whoever claims to be on a perpetual polyphasic schedule mustbe either suffering from a sleep disorder, or be a liar, a mutant, or a person with amulishly stubborn iron-will. Lots of critical mail pointed to the blog of Steve Pavlinawho claims to have adapted well to polyphasic sleep. Pavlina might be the only notablecase to make such a claim, and is used as an example to contradict the claims from myarticle again and again. Even though, in recent months, more claims of successsurfaced on YouTube, Pavlina's loneliness in the success club resulted in more andmore bloggers using his reports as a guideline to polyphasic adaptation. Without adetailed study of this single case or at least some communication with Pavlina himself,I cannot provide a definite reply, and can only voice my skepticism. The most likelyinterpretation might be that Pavlina survived his experiment through sheer will power(he is a motivational speaker that is unlikely to be short on this quality), however, in hisblog he writes "My energy and alertness were excellent once I made it through theadaptation period". Someone suggested that he might be "blessed" with an adaptationmutation. This is the least likely interpretation. Any mutation to a healthy sleep controlsystem is likely to put it out of kilter. Conceivably, polyphasic sleep might be a relief ifthe system lost some of its circadian periodicity, however, such a mutation wouldprimarily manifest itself with a difficulty in obtaining a healthy sleep rhythm with atypical refreshing night sleep, which clearly is not the case with Pavlina. I can onlysuggest the reader gets in touch with Pavlina or skeptically read his blogs to draw hisor her own conclusion. A word of caution though, Pavlina's blog is peppered withmisleading inaccuracies. For example, he writes: "Adapting to polyphasic sleep is likechanging any habit, such as quitting coffee. It may involve some force and struggle fora few days to break the old pattern, but afterwards your new direction feels perfectlynormal, and no ongoing force is required. Day 2 was the struggle. After that it was alldownhill". That "withdrawal" premise underlies the hopes of many polyphasic sleepers.However, coffee is an addictive substance and withdrawal is governed by the rules ofaddiction. Recovering from a jet lag is based on an entirely different mechanism ofsleep phase shift. Finally, "adaptation" to polyphasic sleep is neither a case of "nightsleep withdrawal" nor "night sleep phase adjustment". It is just an attempt to partitionthe circadian rhythm, which is biologically not possible. A degree of adaptation isachieved by the compression of sleep stages that make the schedule more bearable,however, true adaptation manifested by natural waking before the alarm is notpossible!

Puredoxyk

Another case often asked about is that of Puredoxyk - the "inventor" of the "Uberman

sleep schedule". Not the least for her being a woman, which immediately gets thedander up of the "polyphasic women lie" conspiracy theory circle. Again, without adetailed analysis of blogs and multiple new articles on the subject by Puredoxykherself, I should not make speculative statements on her particular sleeping regime.However, what strikes me in Puredoxyk writings is that she instantly rings credible.Let's have a peek at what I will call the Puredoxyk Law:

Six naps no sleep; 4 naps one-point-five hours sleep; 3 naps three hourssleep; 2 naps four-point-five hours sleep; one nap six hours sleep*.* I removed two tiny mathematical kinks from the law which was originallyformulated as: Six naps no sleep; 4-5 naps one-point-five hours sleep; 3 napsthree hours sleep; 1-2 naps four-point-five hours sleep; one nap six hours sleep

Obviously, this law would need to be parametrized to fit a general healthy population.In particular, most monophasic sleepers will find it hard to nap more than once per dayunless all sleep blocks in question are terminated with an alarm clock perpetuating thecycle of sleep deprivation.

We can instantly see a nearly perfect linear nature of the relationship between theduration of the night sleep and the number of naps taken.

Naps = 5.6 - 0.8*CoreSleep

With this formula, the duration of naps will determine the break even point for the totaltime gain on polyphasic sleep. Obviously, that break even point will coincide with thesituation in which the total amount of sleep is constant. After summing up nap timewith sleep using the above formula, we can see that the total sleep time will depend ontwo variables: the number of naps and their duration. After differentiating for thenumber of naps, and comparing to zero, we arrive at the conclusion that the breakeven point stands at naps lasting 70 min. This corresponds with the total sleep time of7 hours. This means that naps that last less than 70 min. will produce a net gain on thetotal amount of sleep in a polyphasic sleeper. It would be interesting to analyzeirregular sleep logs that comply with the above law as they could answer somequestions on the winner in the tug of war for sleep efficiency between the regulatorypowers of the free running sleep and the adaptive powers of the sleep compressioninduced by alarm clock use in polyphasic sleep.

The net time gain in a short-nap regime, obviously does not translate to a brain gain,and this should not be understood as a recommendation to seek minimum total sleeptime. I posed the above problem only as an interesting mathematical relationship,which provides a neat formula for the total sleep debt that might be of use in modelingsleep in conditions where sleep is terminated prematurely (e.g. with an alarm clock).

Neither SleepChart nor SuperMemo account for sleep debt as both have beendesigned for the ideal free running sleep condition. Obviously, any form of sleep debtis unwelcome as it implies unfulfilled neural function of sleep. In short: Instead ofaiming at minimizing the sleep time, we should aim at maximizing the brain effectof sleep.

That Puredoxyk got sufficient experience in sleeping polyphasically to formulate theabove law without any specific logging tools indicates that she needed a pretty vastarray of napping permutations to see the bigger picture, which in this case seemshighly plausible. The Puredoxyk Law can be interpreted as a demonstration of how ahealthy mono- or biphasic sleep can be stretched into a polyphasic phase space withan increasing degree of sleep debt. Puredoxyk herself calls her new sleeping regimethat includes a "core nap" the 3-hour Everyman schedule. This schedule sounds prettysustainable if it is not too heavy on the use of the alarm clock. After all, a third ofAmericans can function reasonably ok despite committing the neural crime of usingthe snooze button on a daily basis with the average use said to be around 3 times.Needless to say, this Everyman schedule stands as a pretty wide departure from theoriginal Uberman formulation that I found particularly harmful.

In the past, I have received a number of sleep logs with pretty irregular sleep patterns(including multiple naps). Those logs were accompanied by some anecdotal evidencethat seems to indicate that those irregular patterns are strongly correlated with somepersonality characteristics. I can be widely speculative here and say that those arepretty neurotic and yet quite creative types (excluding cases that could be attributedto the use of prescription drugs). If that was to be the case, those sleep patterns mightnot be too good for longevity, but even free-running sleep will fail to straighten themout. This indicates that there could be genetic factors involved here, and the "mutationhypothesis" is far more likely to explain a perpetual irregular pattern than a regularfresh&alert Uberman pattern (see Pavlina interpretation). I would even avoid the use ofthe word "mutation" here as those "personality genes" must be pretty widespread inthe modern population. How can Puredoxyk's case be interpreted, I have no idea, but itdoes not seem to be too extreme in its uniqueness, and, as such it can be,probabilistically speaking, deemed credible.

Links

Good sleep, good learning, good lifeSleepChart: Formula for healthy sleepSleep and learning timelinePolyphasic Sleep: Facts and MythsHow to nap

If you are interested in chronobiology and how it affects the feasibility of thepolyphasic sleep, read the following physiology insert.

Chronobiology

Polyphasic sleep adaptation myths

In my original article I tried to mix science with pop science, as well as with anecdote andhumor. Predictably, nearly all comments and criticism referred to the pop part, and nomeaningful reply to the science argument landed in my Inbox. At the risk of having the scienceapproach ignored entirely again, I hereby present a new angle at looking at the art of napping.Hopefully hard data collected with SleepChart and SuperMemo should back up the argumentand add to its illustrative and explanatory power.

Have a peek at the following amazing picture obtained in recent months with the help ofSuperMemo. The graph shows the powerfully biphasic nature of the human circadian cycle.The horizontal axis shows the circadian time, i.e. the time that elapses from phase 0, i.e. thepredicted "end of the night" time. The prediction comes from the circadian model employed inSleepChart and SuperMemo, and is derived from the sleep log collected in SleepChart and/orSuperMemo. The pink line is the predicted alertness derived from the same sleep log datausing the two-process model of sleep developed for the purpose of sleep optimization inSuperMemo (the model is inspired by similar work of Alexander A. Borbely and PeterAchermann). The alertness is a resultant of the status of the two sleep-drive processes: thehomeostatic process and the circadian process. The blue dots are recall data taken from anactual learning process in SuperMemo. In other words: Pink is the model, blue is the data. Bothtell the same story! For skeptics who do not believe in scientific models, blue-dot unprejudiceddata should be the ultimate clinching argument. The graph tells you unequivocally that we gottwo major peaks of alertness during the day. More importantly (in our polyphasic sleepcontext), it also states clearly that there are only two valleys conducive for sleep and/ornapping.

Myth #1 of polyphasic adaptation: a nap is a nap is a nap. Even though this myth is oftenunspoken, it lives deep in the psyche of polyphasic adepts who do not seem to realize themyriad of genetic, metabolic, neural, and hormonal processes that cycle through the humanbody throughout the roughly 24 hour period. Below, I include a general partitioning of thecircadian cycle with a short analysis of what processes occur when a nap is taken at eachselected point of the cycle. Naps taken at different points of the circadian cycles are asdifferent as chalk from cheese. Some are refreshing. Some are a waste of time. Some may beunhealthy (or at least inefficient). Some will last several hours!

Myth #2 of polyphasic adaptation: the circadian cycle can be ignored or abolished, andthe sleep can be reduced to one-dimensional homeostatic process. This myth is unspoken aswell and definitely comes from the lack of understanding of the two-process nature of sleep.Some polyphasic adepts might be knowledgeable enough to have heard of ultradian rhythms,however, little do they realize the overwhelming power of the primary circadian sleepcomponent (as seen in the graph above). Consequently, the myth bears a belief that naps canbe induced at will at any time that is sufficiently far away from the prior nap.

Circadian timing of naps

My original "Polyphasic sleep for dummies" section was not very successful in conveying thepower of two sleep processes in controlling the timing of sleep. Here is another approach froma different angle. Using the graph presented above, let's imagine what is happening when thenap is taken at different times of the circadian cycle:

Phase 0: Waking time: napping in Phase 0 is possible, and largely depends on the history ofprior sleep (see 0 on the horizontal axis in the graph above). Phase 0 naps after a normal nightsleep can be considered as a complement to the night sleep if it was not effective enough.Such naps consolidate with the night sleep in sleep models and are an efficient way ofextending the night sleep in cases when it was interrupted (e.g. by noises, bursting bladder,health issues, etc.). Phase 0 naps after a sleepless nap can serve as an inefficient substitute

for the night sleep. Such sleep will be short, unrefreshing and leave a sleep debt. It will alsointroduce unwelcome oscillations in the circadian system that may take a few days to clear up.Such sleep is often used by night-shift workers to get some mental boost for a day. It is still farbetter than no sleep at all. The rule is simple: if you are sleepy at Phase 0, nap at will. Yourbrain clearly needs more sleep.

Phase 3: Creativity time: napping in Phase 3 should not ever be possible in a healthy well-regulated system (see 3 on the horizontal axis in the graph above). Successful sleep at thistime is an indication of sleep deprivation, poor quality sleep (e.g. due to sleep apnea), sleep ina wrong phase (e.g. taken too early), sleep disorder (e.g. narcolepsy), etc. This is probably thehardest time to nap of all. However, I am not aware of any bad effects of such naps for healthor for sleep control systems.

Phase 5: Pre-siesta: napping in pre-siesta slot is possible. However, such naps are likely tobe short and not as refreshing as Phase 8 naps. They are also more likely to be REM-rich forcircadian reasons. Those early naps can probably be recommended to people who suffer fromsleep-onset insomnia, and who still want to boost the second half of their day in terms ofalertness and creativity.

Phase 8: Siesta: perfect time for napping. As it can be seen in the graph, this is the periodwhen the mental performance is at its mid-day nadir. It is not true that the nadir is caused by ahefty lunch (even though meals have a big impact on sleep control). The nadir is a naturalexpression of the circadian wave in sleep control. This circadian low time comes at the roughlysame clock time as the subjective night nadir at a roughly 12 hour shift (e.g. if the middle ofyour night falls at 3 am, naps at 3 pm could be most effective). This is well explained in "Howto nap". Dr Stampi also praises the value of siesta. Its benefits have been confirmed bynumerous studies. It has been practised for ages in many regions of the world. It will definitelytrickle into the corporate world as human productivity becomes increasingly dependent onone's creative powers.

Phase 11: Evening: this is not a good time for napping. In a healthy cycle, napping might behard to achieve or impossible. However, even a minor degree of sleep deprivation will producea nap that might trigger the control mechanisms responsible for the full-night sleep. Late napsare likely to be rich in NREM sleep and rob your night sleep of the vital SWS component. Thosenaps can last far longer than siesta naps. They can make you groggy. Worst of all, they cancompound insomnia. Unfortunately, this is a type of a nap that a huge proportion of studentstake! Forced to wake up at indecently early times for school, kids and students struggle semi-conscious through school hours with negligible progress in learning. Learning in such a stateonly magnifies the pretty universal hatred of school. Phase 11 nap is then the only way tosurvive the day and get some actual learning done in the evening. The body clock shifts thesubjective night to the morning hours. The positive side effect is that evenings can be filledwith effective studying. The negative side effect is that the student finds it impossible to fallasleep before 3-4 am, and welcomes the new bright school day with an alarm clock that ringsin the middle of the subjective night. This perpetuates the cycle of suffering and school hate.Nobody has ever estimated the global consequences of this phenomenon that includes animpact on adolescent attitudes that are notoriously fraught with problems. Neither has anyonecome up with a practical solution (shifting school hours usually results in kids "adapting" to thenew cycle by shifting their bed time as well). I am not able to recommend a solution here either.Skipping evening naps might be better for the quality of night sleep and for the stabilization ofthe circadian cycle in the earlier phase, however, that would effectively rob those students oftheir only time in which they can learn. Those evening naps are also the only meager substitutefor free-running sleep that those young brains crave. The only time when the brain gets what itwants. If I was to answer: to nap or not to nap, I would probably have to admit that eveningnapping is the lesser evil in a majority of cases.

Phase 14: Pre-sleep: this is a particularly bad time for napping. Initiating naps at this timeshould be relatively easy. However, pre-sleep naps are likely to produce one of the followingunwelcome outcomes: long-nap-short-night or long-night-early-waking (depending on the

current status of the sleep control system). A pre-sleep nap is likely to result in triggering thenight sleep sequence. However, this sequence is not unbreakable, and can result in earlyawakening combined with the difficulty in launching back to sleep. This is particularly likely ifthe homeostatic sleep process generates substantial sleepiness while the circadian process isnot yet mature for the night sleep. As a result, such a pre-sleep nap can yield less total sleepthan a normal night sleep. This long-nap-short-night will not entirely fulfil the physiologicalfunction of sleep. Consequently, your alertness levels for the next day are likely to dipsubstantially. The less unfortunate outcome of a pre-sleep nap is if you successfully trigger theuninterrupted night sleep sequence. However, you will likely prematurely run out of thehomeostatic process before the circadian function of sleep is completed. You will probablywake up earlier than usual. This is the long-night-early-waking outcome that produces nightsthat are amazingly unrefreshing considering the fact that premature sleep is often much longerthan an ordinary night sleep. The reason for this low sleep efficiency is probably the scarcity ofREM sleep which is strongly circadian. Moreover, for circadian reasons, your morning is likelyto be unusually sleepy!

Phase 18-24: Night sleep: if you try to nap in Phase 18-24, you are bound to trigger a normalhealthy night sleep. This is ok as long as you do not get down to "napping" with the evil intentof stopping the process in 20-40 min. Here is were the pain of polyphasic sleeping becomeshardest to bear. As Dr Stampi noticed two decades ago, it is not the problem with stayingawake or with falling asleep that is most exasperating. The most painful part of a polyphasiclife is when your brain wants to trigger the night sleep sequence and a polyphasic adeptstubbornly disallows it! This is as bad an interruption as any other abrupt stop to an all-or-nothing physiological process (urination, defecation, orgasm, swallowing, heart beat, sneezing,coughing, childbirth, and the like). Many polyphasic bloggers note: "I noticed that when mynaps get longer, I get groggy. So I try to keep them under 20 min". Duh! If you do not launchthe night sleep sequence, you will not suffer the pain of interruption. Why nap in the first placethen? It's easier to delay defecation than to stop it in the middle. The most unusual night-timenap control method I have encountered was... "I keep lots of junk in my bed. That keeps mynaps short"!

Important! The two alertness valleys are biologically dissimilar! As it will be shown later,only the night-time valley can produce a typical long-drawn periodic NREM-REM interplay witha gradual increase in the proportion of REM. The subjective night period is marked by acharacteristic increase in the release of melatonin. The length of siesta sleep, as shown below,in the biphasic sleep graph, is 4-20 times shorter than the natural night sleep. Phase responseis elicited by stimuli that precede or follow the night sleep. However, the same stimuli my affectthe timing of the siesta nap, which in turn may have an indirect impact on the cycle phase.

Some chronobiological findings from SleepChart and SuperMemo relevant to polyphasicsleep

This section provides some data that fortify the view that polyphasic sleep is not entrainable.To follow this text you may need some basic understanding of chronobiology, SleepChart andSuperMemo.

Chronobiology vs. SleepChart

Understanding the control mechanisms that produce sleep and wakefulness is extremelyhelpful in individuals suffering from a number of sleep disorders, in particular, insomnia andphase-shift disorders. Simple measurements of circadian variables and simple tools ofchronotherapy may bring sound sleep to those who often struggled for years with insomnia,unsatisfying sleep, or sleep in wrong hours. Better understanding of chronobiology could alsohelp extinguish dangerous practices such as poorly planned shift-work, disrespect for healthconsequences of the jet lag, cumulative sleep deprivation and the Internet fad of polyphasicsleep.

A few years ago, we have published a freeware application for charting sleep data and

circadian graphs (see: SleepChart). SleepChart makes it easy to analyze a person's sleepinghabits in terms of circadian timing, effects of wakefulness on phase shifts, homeostaticsleepiness, etc. In this short narrative, a few conclusions are drawn from the comparison ofSleepChart data collected by healthy sleepers and sleepers attempting to adapt to polyphasicsleep schedules.

Courtesy of the numerous contributors who sent in their data, we can draw a number ofinteresting conclusions. The most compelling one is probably the confirmation of thehypothesis that we might be facing an epidemic of Delayed Sleep Phase Syndrome (DSPS) inyounger generations, esp. among students and people employed in high-tech jobs. Theepidemic is a result of an ever-growing discrepancy between the environment in which humansand their primate ancestors evolved over the last several million years, and the environment inwhich we live today with electric lighting, Internet, computers, TV, rat race, and 24-hoursociety. The increasing gap between lifestyles and biology leads many to seek radical solutionsand take on drastic measures. A quick survey of those who attempted the dangerouspolyphasic sleep experiment reveals an interesting truth. Although the wish to squeeze in morewaking hours into a day is a very appealing concept on its own, most of the "experimenters"began their interest in polyphasic sleep as a result of troubles with achieving refreshing sleep.

Most of healthy individuals are either biphasic, "crypto-biphasic", or monophasic. In thepresented graphs, tightly spaced cluster naps are merged for clarity of graphs using aheuristic algorithm employed in the SleepChart application. SleepChart was designed for freerunning sleep, and some readings may thus be distorted for other conditions. In particular, youcannot map circadian or homeostatic sleep components using just behavioral markers withoutthe free-running sleep condition.

Biphasic sleep

In the presented graphs, the blue line corresponds with the ability to initiate sleep at any givencircadian time. It aligns well with the alertness graph presented earlier. It aligns well with boththe learning data, as well as the two-process sleep model.

The red line corresponds with the ability to maintain sleep. It reveals what is not visible in thealertness graph shown earlier: siesta naps cannot last long and will always be subject to anearly natural termination (low red line under the first blue peak). In contrast, the period ofsubjective night is the only time of day when sleep can and should last longest (usually no lessthan 4-5 hours). The red peak is the reason why polyphasic adepts crave for "core sleep",wake up groggy, and need heavy alarm artillery to wake up in this critical period.

Monophasic sleep

Monophasic sleep graphs will often show small siesta-time peaks due to the fact that even thepurest monophasic sleeper hits crisis days in which a postprandial nap brings a welcome relief.Due to its "crisis nature", such nap may last longer than it is the case in a typical biphasicsleeper. This is particularly visible in irregular sleepers who show less discipline in shelteringtheir natural regular sleep hours.

Preference for night sleep

In free-running sleep of an irregular sleeper or in cases of DSPS, we can see the impact ofnighttime on the ability to initiate and maintain sleep. Independent of the innate circadiancycle, light has a powerful impact on sleep. In particular, its phase-shifting capacity will alwaysensure that humans naturally gravitate towards sleeping at nighttime. Only the advent oflifestyle that involves electricity and 24h work cycles triggered the present epidemic of sleepdisorders, which indirectly contributed to the appeal of concepts like "Uberman sleep".

The above graphs with the horizontal axis taken as the time from waking can also be

interpreted as a phase space. It can be demonstrated that no trajectory in the phase space willlead to an entrained polyphasic sleep. When alarm clock and/or sleep delay are introduced intothe system, it may become chaotic. However, in free running mode, in quickly stabilizes arounda roughly biphasic rhythm, often with a degree of phase-shift dependent on the lifestyle(primarily: interaction with zeitgebers and timing of stimuli affecting the endocrine system).The timing of phase-shifting, excitatory and inhibitory stimuli, even if they are repetitive andregular, may still lead to a degree of chaos in the system. This occurs if the period of theircycles is different from the period of the entrained circadian rhythm.

Polyphasic sleep vs. SleepChart

After publishing "Polyphasic sleep: Facts and Myths" a few dozen young men wrote to merequesting assistance in entraining polyphasic schedule. Ethically, I could not proceed in anyother way but from starting to attempt to dissuade the young enthusiasts from proceedingwith their polyphasic experiment. Needless to say, these are not the types that are easilypersuaded to veer off their way. As I wrote previously, these are "rebellious men ready to seeknew ways for maximum productivity". No scientific argument can be persuasive in such cases.After all, all reasoning can easily be quashed with "science does not yet have all the answers".None of the young rebels succeeded in entraining polyphasic sleep, yet some were persistentenough to provide some SleepChart data that sheds some more light on the implausibility ofthis sleep schedule.

Polyphasic sleep (Stampi yachting research)

In data obtained by Stampi one can see the forbidden zone in the first part of the day and clearhomeostatic preference for the hours 15-24 of the waking day. The circadian curve ismeaningless due to the fact that sleep is artificially interrupted. However, it would likely alignwith the blue sleep initiation curve (sleep initiation is easier and will preferably come in lowcircadian zone corresponding with the subjective night).

Uberman sleep attempt

Uberman sleep logs

The picture shows the three most disciplined Uberman attempts I managed to collect fromGreg (A), Bryan (B) and Claudiu (C).

At 9 days, Greg's attempt lasted longest and was quashed by the clustering of "core" sleep inthe early morning hours towards the end of the experiment.

At nearly 5 full days, Claudiu's attempt was the longest "pure Uberman" before experiencinghis first lapse into an extra nap. It is equally notable for its never having missed a single napbeyond Day 1. It is important to note, however, that many nappers find it difficult to determineif they actually fell asleep during naps that come in forbidden zones. What they mark as a napmight have actually been a few short moments of microsleep.

Last but not least, Bryan's attempt was still underway when I closed the period for datasubmission for this article. If he succeeded beyond the presented period, I will still try toupdate his case via an appendix to this article.

Two-process sleep model vs. polyphasic sleep

The data collected from Greg, Bryan and Claudiu can now be fed to SleepChart or SuperMemoto apply the two-process model that makes it possible to predict alertness on the basis of thehistory of sleep (to inspect your own data in SuperMemo 2008 use Tools : Timeline, chooseFile : Import SleepChart file, and use Shift+click on your sleep log to inspect sleep propensityat the chosen moments of time in the sleep log).

In the presented graph, the thick red line represents estimated alertness (computed using the

same model as in the biphasic sleep graph). It is easy to see that its shape depends on thecircadian phase at which naps occur (the circadian sleep propensity is marked in light blue).The graphs were juxtaposed so that to align nap timing while having them occur at differentcircadian phases that produce different alertness profiles.

Even though the sleep model used in SleepChart/SuperMemo applies to free running sleep, thesymmetry of Uberman napping nullifies the need to correctly predict the circadian peaks andvalleys (wherever the peaks occur, they will largely intersect with the nap grid at random). Inaddition, if regular sleep data are collected before the polyphasic sleep experiment, correctsubjective night estimations from that period will carry over across the first few days of thepolyphasic experiment. After all, only phase shifts can position the wave phase. The samemechanisms that makes polyphasic sleeping so hard, can also be used to explain it with themodel designed to serve free running sleep condition.

Polyphasic rollercoaster

What primarily emerges from the graphs presented above is the typical "rollercoaster effect"of the "Uberman sleep". Unlike a typical sleeper who wakes up refreshed and goes to sleeptired, a polyphasic sleeper will experience moments of extreme euphoria (e.g. at 4 am in themiddle graph), and discouraging downers (e.g. 15:00 in the bottom graph). The presentedalertness estimates correlate well with the subjective "focus and motivation" assessmentsmade by the sleepers themselves. In the bottom graph, where a nap at 23:00 produced amajor surge in alertness, the nap at 3 am delivered nearly nothing. This produces a typicalrollercoaster of enthusiasm and self-doubt in a polyphasic sleeper. After short naps that occurat the minima of circadian sleep propensity, a polyphasic sleeper may reach heights that are

not known to ordinary sleepers. Those surges of enthusiasm verging on euphoria are prettyunique due to the fact that an ordinary sleeper nearly never naps at circadian sleep propensityminima. Those moments can make a polyphasic experimenter update the blog with "never feltbetter - creativity at its maximum". At the same time, some naps can only make things worse.For example, the nap at 3 pm in the bottom graph taken on June 23 does not seem to produceany boost in alertness. It was then followed by an hour long "correction" that would not boostalertness either. Moreover, the cresting circadian wave will produce the unpleasant feeling ofgrogginess (i.e. sleep inertia) that should be familiar to shift-workers. That combination ofsleep process variables is also responsible for the foggy head of the jet lag. This illustrateswhat Stampi noticed in his experiments that it is not hard to stay awake on a polyphasic sleep.The hardest thing is to wake up from naps that occur at the circadian crest.

Polyphasic sleep attempt

In the presented example, a polyphasic adept started with 4 naps of 30 min, and a "core sleep"of 3 hours at 20:00 with an intent to reduce it to 30 min overtime. However, the adept keptfailing to fall asleep during some naps and continued to struggle with alertness in some wakingslots. The core sleep could not be shortened without further sleep deprivation. Instead, thecore sleep increased in length slightly and moved to a later hour. Gradually, daytime napsstarted disappearing until the adept moved to a typical biphasic sleep of 5-6 h in the evening,with a 30-60 min. nap in the morning (and an occasional extra nap during the day if the coresleep resulted in heavy sleep deprivation). One year later the adept is nearly monophasic withonly one rule leftover, "try to go to sleep before midnight".

Phase response curve (PRC)

SleepChart implements a concept of the Recursive Phase Response Curve (rPRC). Thecurve is recursive because it is first obtained by computing the impact of phase shifts in sleepblocks in relation to the middle of the subjective night line computed using statistical methods.Once the first approximation of rPRC is obtained, it can be used to produce a betterapproximation of the middle of the subjective night line that is then used to generate a betterapproximation of the rPRC. A few iterations of such a process are sufficient to produce thebest fit of the rPRC that corresponds well with the actual sleep data (SuperMemo uses a fixedrPRC that roughly corresponds with rPRCs obtained with SleepChart). Whereas a typical PRC

employed in chronobiology maps the response of the sleep system to a single stimulus (e.g.light, exercise, melatonin, or various chemical agents), rPRC is the resultant of all natural sleepdelaying factors (incl. light, activity, stress, etc.). It can also be interpreted as a PRC, in whichthe waking activity forms the input to the free-running sleep system. Unlike a PRC whichresponds to a shifting factor, rPRC responds to the evening phase shift caused by the samefactor. As such, rPRC is not a de facto PRC, and all departures from the free running conditioninvalidate the computation. The main advantage of rPRC is that it can be derived from sleepdata without collecting blood samples, saliva samples or taking core body temperaturemeasurements. This way, SuperMemo can correlate learning with sleep models that use onlyplain sleep log data as input.

In the presented graphs, Sleep delay (h) stands for retirement delay and equals the differencebetween the actual retirement hour and the optimum retirement hour as computed bySleepChart from the prior history of sleep. As the measurements refer to free-running sleep,no phase advance data is available due to the natural way of waking. The causes of sleep delaymay include light, social interaction, stress, a conscious decision to delay sleep, exercise,ingestion of caffeine, ingestion of alcohol, medication, etc.

Phase shift (h) stands for a phase shift and equals the difference between two exponentiallyweighted waking hour averages on two successive days: the day on which the retirement delayoccurred and the following day. Instead of the retirement hours, waking hours were comparedas these are less affected by the homeostatic shift caused by the actual delay thusrepresenting a truer reflection of the actual phase shift.

The flattening of the curve (as compared with a typical PRC) is caused by the recursivereference to actual sleep block data, which results from the fact that plotting the circadian lowby SleepChart is an approximation based on the same sleep block measurements. As a result,polynomial approximation shows a slight increase in phase shift with increasing delay, which isnot the case in typical PRC plots. The deviation of the retirement hour from the optimumretirement time may result from either environmental delay factors or from the approximationerror resulting from heuristic procedures used to plot the circadian function, while sleep onsetusually occurs naturally at optimum physiological time. The inherent asymmetry of the graphcomes from the fact that earlier retirement is nearly always natural, while delayed retirementmight be natural or forced (i.e. resulting from delay factors).

The graph presented below implies that in this particular case, delaying sleep by four hoursresults in a shift of sleep phase equal to 1.4 hours (which seems to be close the the maximumshift possible). Phase advance would require a natural onset of sleep that preceded theoptimum retirement time by as much as 6 hours. Retirement at optimum hour results in thenatural daily delay, in this particular case 1.0 hour, typical of DSPS disorders or conditions ofisolation from zeitgebers (e.g. constant lighting).

Polyphasic sleep rPRC

It is possible to feed SleepChart with data obtained from "Uberman experiments". Obviously,the mere departure from free-running condition makes the outcome hard to interpret. Even therecursive nature of the procedure used to obtain rPRC cannot effectively cope with the lack ofthe leading circadian crest. With all that in mind, it is still interesting to peek at "UbermanrPRC" as it nicely reflects the chaotic nature of the sleep system subjected to a polyphasicexperiment.

A polyphasic sleeper pushes his sleep phase back and forth largely at random. That can onlyresult in a chaos and complete asynchrony of all neural, endocrinal and biochemical processesdepending on the circadian component of the sleep cycle. One might expect serious healthconsequences of such a chaotic input to the system; however, natural defense mechanismsmake life quite miserable for those who attempt a struggle against the natural sleep cycle. As aresult, those who attempt polyphasic sleep are doomed to drop out sooner or later. There is,however, some hard-to-estimate risk of long-term impact of a "polyphasic experiment". This,in the order of decreasing likelihood, could include:

desensitization to signals sent by the sleep control systemlong-term instability in the sleep control systemdamage to nerve cells involved in the control of the circadian cycle

The first possibility can actually be observed in shift-workers and people running a constantbattle with sleep deprivation. In those individuals, the concept of "refreshed mind" and"refreshing sleep" becomes hazy, and one can observe an increased tolerance to permanentdegree of tiredness coming from insufficient sleep or sleep in a wrong circadian phase. Inother words, a degree of fatigue becomes a norm.

Instability of the sleep control system is also observed in shift-workers. It is not clear if shift-induced instabilities can become chronic or are fully reversible in a relatively short time. Evenin a perfectly tuned sleep control system, minor rhythm perturbations, such as a switch to theDST, can produce regulatory ripples lasting for days. Larger perturbations might, in theory,result in uncoupling of master and slave oscillators with a particularly slow return to fullystabilized control. Perhaps this kind of uncoupling is the primary factor that underlies a myriadof disorders that plague shift-workers in the long-term.

Circadian wave function is like an electrocardiogram: if you try to become polyphasic, it is as ifyou wanted to change your heart rhythm and produce a separate contraction of right and leftatria, or separate repolarization of left and right ventricles, etc. Your healthy ECG will alwaysshow the same regular pattern. You can phase shift your sleep as much as you can speed upyour heart with exercise. Yet you cannot abolish the primary circadian rhythm as much as youcannot abolish the typical ECG pattern. Neither can you change the proportions of sleep zones

as much as you cannot change much the proportion of the PR interval in the ECG period.

Sleep block length distribution

SleepChart can also be used to invalidate the claim that sleep blocks cluster in multiples of 90min. (a popular polyphasic myth). Sleep block length distribution for a monophasic sleeperbelow: 1, 2, 3, 3.5, 4, 5, 6, 7, 8, 9, 10 come only from inaccurate marking by the subject. Thereis no 90 min. trend discernible.

Conclusions

polyphasic sleep results in chaotic phase-shift responses without any noticeablecircadian shift (in cases studied)due to a lack of direct entrainment response from the sleep control mechanism, long-term healthy adaptation to a polyphasic sleep pattern is not possible in healthyindividuals

a marked portion of the young studying generation may be affected by a degree of aDSPS disorderI suggest that the increase in DSPS is most likely caused by the modern lifestyle

Links

Phase Response Curves: What Can They Tell Us about Circadian Clocks?