Quad Core 0

Default Quad Core 0

The Quad Core (QC) family of schedules, the newest schedule group, are very unusual in structure; thus, they are very unpopular due to the intrusive sleep blocks, scheduling limitations and wake time activities. They are a series of schedules that contain 4 core sleeps, totaling at least 6h sleep. So far, the only tried-and-successful schedule in this category is Quad Core 0 (QC0). Mostly because of the heavy focus on core sleeps, QC schedule(s) have a very low number of naps, or no naps at all.

Similar to Tri Core sleep, an advantage of QC schedule(s) is that they divide the day into several awake blocks with 4 core sleeps spreading across the day.

  • Because different core sleeps yield different percentages of sleep types, this supports alertness and wakefulness and keeps homeostatic pressure low.
  • Unlike schedules with a 6h uninterrupted core sleep, QC promotes deeper sleep compression with its single-cycle core sleeps.


  1. History
  2. Mechanism
  3. Adaptation
    1. Research
    2. Adaptation Pathway for QC0
  4. Difficulty
  5. Alternate Variants
  6. Lifestyle Considerations


The first QC schedule, Quad Core 0, has no naps and only 4 core sleeps. It was briefly mentioned in the Ubersleep book by Puredoxyk under the name  “Alternate Segmented” variant. However, there was no adaptation success ever reported until 2020. The book did not specify optimal scheduling either. There have been some attempts up to date, but with limited success.

Currently, QC0 is one of the 5 polyphasic schedules with only core sleeps (the other 4 being Segmented, Siesta, CAMAYL and Triphasic).


  • Similar to Tri Core 1, the default QC variant involves having 3 core sleeps concentrated around night hours to limit inconvenient daytime sleep as much as possible. The fourth core is in a position similar to the daytime Siesta core to balance the wake gap.
  • One core sleep is more SWS-oriented, one is REM-oriented and the remaining 2 contain mixed stages. Because of the segmentation into multiple small core sleeps, sleep repartitioning and quality is expected to be deeper than a usual, uninterrupted 6h core sleep (e.g, E1 core).
  • SWS deprivation symptoms are less visible on this schedule than on Triphasic, TC1 and other low-total-sleep schedules. This is because there are 4 core sleeps to support SWS. However, as adaptation progresses, it is also normal to run into SWS wakes especially in the core sleeps around SWS peak and early second half of the night hours (00:00-04:00 AM) when SWS pressure still lingers.
4 equidistant core sleeps

It is also possible to schedule Quad Core 0 equidistantly, which resembles a Dymaxion structure with core sleeps. This may facilitate falling asleep as the wake gap between each core is increased to 4h30m rather than being much closer together at night.

However, even this distribution so far has reported no success.


Since Quad Core 0 already has a decent amount of sleep, transitioning from Segmented sleep likely will not help. Thus, a cold turkey adaptation is likely superior. 

Research on adaptation mechanics of a similar polyphasic schedule

Although the research focus was not on Quad Core 0, there are inherent similarities between the studied polyphasic schedule and QC0. This polyphasic schedule has 8 sleep blocks of 60m each and spread equidistantly. Researchers coined it an experimental “3-hour Day” polyphasic schedule1; participants slept for 1h and stayed awake for 2h, totaling 8h TST.

Participants also slept on a monophasic pattern consistently (8h TST) before transitioning to this non-reducing polyphasic pattern. The cycle rinsed and repeated for 9 days before a recovery on monophasic sleep. Below is the napchart of the exact sleep times of the schedule. 

All in all, the high total sleep, somewhat similar distribution of sleep blocks and sleep duration on this polyphasic schedule may apply to QC0’s adaptation. A 60m sleep block also somewhat resembles a “mini-core” sleep compared to the 90m equivalent. 

3-hour day polyphasic schedule


  • Only 56% of sleep duration from these sleep blocks was actual sleep throughout 9 days. Meanwhile, 90% of monophasic duration was actual sleep. 
  • REM sleep deficit became apparent. 
  • Subjects managed to get ~80m of SWS, which was 75% of their monophasic baseline. 
  • From day 7 to day 9, the percentage of sleep stages to total sleep duration was the same as on monophasic sleep. This occurred despite the “reduction” in total sleep time; participants still could not fall asleep in certain sleep blocks.
  • While one subject only obtained a minimal amount of REM sleep in the last 3 days, another did obtain gigantic REM numbers.
  • All subjects became irritated due to abrupt awakenings at the 60th minute mark, where most sleep occurred. 
  • All subjects were most sleepy and irritable from 10 PM to 9 AM. 
  • Across 9 days, the percentage of light sleep decreased while the overall percentages of REM and SWS increased. 
  • The majority of REM sleep occurred in sleep blocks around 6 AM, 9 AM and noon
  • Subjects could only get very little sleep in sleep blocks around 6-7 PM, 9-10 PM and midnight-1 AM. 

Analysis from Community Standpoint

  • The 3-hour polyphasic schedule was very inefficient. Sleep blocks were too close to each other, and wake periods were too small. As a result, sleep onset remained high for many of the unnecessary sleep blocks. By the end of the study, subjects only managed to fall asleep in ~4-5 sleep blocks each day. 
  • The community do not recommend scheduling 60m sleep blocks, because they only lead to more sleep inertia and irritating awakenings, as demonstrated in the study. There is also more chance to oversleep a 60m duration than a 90m duration. 
  • SWS deprivation was present, but not as punishing as REM deprivation. 
  • The reduction of light sleep percentage and a gradual increase in REM and SWS suggests an increasing sleep efficiency. More REM and SWS are heading into each sleep. This was an ongoing adaptation
  • Since the participants only stayed on the schedule for 9 days, the adaptation was far from complete. It may also be completely unadaptable because of the poor scheduling of sleep. 
  • Negative mood change is also common during polyphasic adaptations. This is an effect of sleep deprivation. 
  • The varying amount of REM sleep between the two subjects could be because of differences in REM requirement and repartitioning speed. 
  • Despite being a non-reducing schedule, it is still vastly different from monophasic sleep in terms of structure. Thus, strict sleep times are necessary to adapt. 
  • The majority of REM sleep occurred around morning hours, which supports the circadian pressure of REM sleep. This is also similar to monophasic sleep, where the last cycle(s) around sunrise hours contain predominantly REM sleep. 

Adaptation Pathway for Quad Core

Based on the research of the 3-hour day schedule, we derive a possible adaptation route to Quad Core 0 below. This route will roughly map out the process of repartitioning of vital sleep stages. 

  • The adaptation first starts with high sleep onset in certain core(s) because of a high total sleep. 
  • Most light sleep and some SWS are in the core sleeps; some amount of REM sleep likely will appear in the core(s) out of SWS peak or near sunrise hours. This behavior is the same as any regular sleep cycle
  • SWS and REM deprivation will start to build. Those with low SWS requirements will most likely have near intact SWS count, because there are 4 core sleeps to afford SWS. Thus, their SWS pressure will remain low. Overall, the repartitioning of REM sleep will be more intense than that of SWS throughout the adaptation; this is because SWS can initially reside in the cores as REM remains minimal. This assumes sleepers can fall asleep in all scheduled core sleeps as adaptation progresses. 
  • As REM pressure builds up, both SWS and REM will be repartitioned into each core sleep. The core sleeps near SWS peak will contain more SWS, and the same for REM at REM peak. Light sleep percentage will also reduce. 
  • Finally, SWS and REM pressure reach an equilibrium. Waking up from all core sleeps is refreshing and energy level throughout the day becomes stable.
  • A core near or at sunrise hours will contain predominantly REM, while a core around SWS peak hours will heavily favor SWS. With this feature, Quad Core 0 also possesses the characteristics of Dual Core sleep.


  • Despite looking to be a somewhat “easier” Triphasic variant with an extra core sleep, most inexperienced polyphasic attempters reported difficulty falling asleep in some sleep blocks, especially the cores during graveyard hours when adaptation first begins.
  • It is then increasingly difficult to handle SWS/REM wakes at the end of each core sleep as sleep onset issue remains.
  • This is most likely because of the schedule’s total sleep and distribution of sleep blocks, which does not initially raise homeostatic pressure high enough to facilitate sleep.
  • Finally, poor quality core sleeps result in an oversleep when they finally manage to fall asleep in a core as sleep pressure becomes high enough.


Meditation & sleep timing tips on QC0
  • If is impossible to fall asleep in a core after lying down for ~20m, one should wake up and wait for the next core sleep. This is much better than trying to fall asleep and risk SWS wakes.
  • As part of a typical 90m core sleep, failure to fall asleep fast enough will result in mid-cycle wakes; this makes adaptation to QC0 very challenging, and inexperienced sleepers should NOT attempt this schedule.
  • Meditation methods as a way to relax and aid the body in preparation for sleep may be useful at an early adaptation stage for this schedule.
  • Alternatively, refer to the section about how to deal with sleep onset issues here

Lifestyle Considerations

Research on lifestyle

Interested in a research paper on Quad Core sleep schedule? Check it out here. 

Alternate Variants

Because of the typically constraint scheduling, QC0 has very limited scheduling variations. 



To date, there has been one successful attempt at this variant of Quad Core. The attempter was still a teenager, and has an overall high sleep drive. As a result, it turned out that Quad Core was a strong option, as the adaptation completed after ~48 days. There were reportedly medium, but not severe cognitive or physical deficits during the entire time on the schedule. The adaptation completion phase was stable and progressed gradually. 

However, there are a couple things to note:

  • For regular individuals with normal sleep requirements, QC0-extended only seems to exacerbate the sleep onset issue in each core. 
  • QC0-extended barely has any viability for long-term; the only reason it can be sustainable is during pandemics like the Covid-19 currently. Because it is a “norm” to work at home, such constrained polyphasic variants become possible. 
  • As of date, QC0-extended is a viable polyphasic schedule for experimentation. Those who prefer to sleep in longer chunks may be interested.
  • The high total sleep may suggest that teenagers may still benefit from a polyphasic regime. 7.5h total sleep is around the non-reducing sleep duration for a lot of monophasic people. 
  • The core sleep around SWS-peak hours extends to 3 hours, which is 2 full sleep cycles. This serves to help ease the adaptation process, and secure sufficient vital sleep stages.  

Aside from the listed factors, the adaptation difficulty and disproportion between total sleep time and social time viability will always make QC0-extended an unappealing choice. As such, even non-reducing Triphasic may be a better option. 

Overall Considerations

Work-from-home lifestyle on QC0
  • QC0 only benefits work-from-home occupations and individuals with higher sleep requirements than average (at least 8.5h and up to 9.5h monophasic). These individuals need a large enough sleep reduction to fall asleep in all 4 cores.
  • With 4 core sleeps, it can support physical activities to some extent (assuming normal SWS requirements and some increase due to exercising).

Eventually, though, Quad Core 0 is still considered a subpar choice to Triphasic-extended, which is more beginner-friendly and sees plentiful success; it also faces stiff competition from other more popular multi-core schedules (Dual Core and Tri Core) in general.

The strongest reason one would adapt to this schedule first would be to transition to CAMAYL to gain a lot of flexibility in scheduling core sleeps. The flexible cores can then assist in a more hectic, changing lifestyle.

Main author: GeneralNguyen

Page last updated: 26 July 2021

  1. Weitzman, E. D., et al. “Effects of a Prolonged 3-Hour Sleep-Wake Cycle on Sleep Stages, Plasma Cortisol, Growth Hormone and Body Temperature in Man.” The Journal of Clinical Endocrinology and Metabolism. 1974;38(6):1018–1030. doi:10.1210/jcem-38-6-1018. [PMC]