Dual Core 2


Default Dual Core 2

Dual Core 2, or DC2, is the second dual core schedule. It is a logical upgrade from DC1 with the addition of 1 nap and some sleep reduction from the core sleeps. The total sleep of DC2 hovers around the hospitable zone for long-term sustenance, approximately ~5-5.5h of total sleep each day. DC2 has moderate adaptation difficulty, and should be achievable with sufficient efforts. 


  1. Mechanism
  2. Adaptation
  3. Alternate Variants
    1. Modified Core Durations
    2. Pronap
    3. DC2-extended
  4. Lifestyle Considerations


With 2 core sleeps placed around the sleep peaks and 2 supplemental naps in the day, Dual Core 2 is similar to E3-extended in sleep distribution; it also offers a decent napping frequency to learn the napping behavior. DC2 in a way also resembles E3, except that the first nap of E3 is now the second core in DC2. DC2 possesses typical traits of a Dual Core schedule.

  • The first core sleep is typically longer than the second core sleep to obtain ideally most or all required SWS. With a 3h core (2 full cycles) in SWS peak hours, SWS is likely intact after repartitioning is completed. Thus, SWS deprivation symptoms on DC2 are overall a lot milder than schedules with only 1-cycle core sleeps.
  • The second core favors REM sleep.
  • The naps provide more alertness boost to sustain the long daytime wake period as the core duration becomes shorter; they also meet the remaining REM sleep requirements. The second nap on DC2 may not give any REM sleep, and just NREM2 or trace SWS instead. It is usually around mid/late afternoon (e.g, after ~4 PM), which may not favor REM sleep.
  • Because of the reduced total core duration compared to that of DC1, an extra nap is mandatory to compensate for the reduced amount of REM sleep in the second core of DC2.

Changes in Core Length Proposition

Over the years, there have been some changes from the Discord community compared to Polyphasic Society regarding DC2. Refer to the PDF attached below for more details.

Are the stock core lengths on DC1 and DC2 valid

Other Comparisons

In addition, DC2 is also a middle ground between the easier DC1 and the advanced DC3. The total sleep is not as high as DC1-extended and not as low as DC3; this gives DC2 a favorable zone of total sleep for flexing sleep after adaptation.

The total sleep is equivalent to E2, but the splitting of core sleeps will provide a deeper core experience for the first core; the second core also gives a lot of vivid dreaming experiences.

The wake gap between 2 cores is also large enough for certain favorite nighttime activities; this includes somewhat mentally taxing duties without having to worry about cooling down for the second core too soon.

  • It is also possible to have a 5-6h wake gap from the morning core to the first nap, and another ~4-5h to the second nap.
  • 4 sleeps per day also renders the wake gap between each sleep more manageable than on E2. Skipping one nap as a result may be tolerable during adaptation, as long as this does not happen too often.


Cold Turkey

From the community’s exposure to Everyman and Dual Core sleep schedules, multi-core schedules (more than 1 core sleep) seem harder than to schedules with only 1 core sleep (e.g, Everyman). This is except for naturally segmented sleepers who are used to sleeping in more than one core sleep.

The repartitioning of vital sleep stages into both core sleeps becomes more complicated than into only one core of Everyman; this also doubles the chance for SWS wakes from both cores during adaptation.

Thus, adaptation to Dual Core 2 in general is at least as difficult as E2‘s, or possibly as challenging as to E3 (3.5h core) for non-natural Segmented sleepers. Initially, splitting the monophasic core sleep into 2 smaller cores cold turkey can result in a much rougher wake from the first core. 

Gradual Adaptation

Gradual adaptation from DC1-extended

Alternatively, a gradual adaptation method from DC1 is also viable, but it also has more limited success than the cold turkey method. Transitioning from DC1-extended seems like a good move; either core of DC1-extended will remove 1 full cycle, while an extra nap is added to the schedule. 

It is also worth noting that after completing the adaptation to Dual Core 2, one can proceed to flexing the naps and the core(s). This is a flexing adaptation to adapt to DUCAMAYL. Alternatively, DC3 can also be the next step. 

Alternate Variants

Over the years, there have been a lot of changes in Dual Core 2 scheduling. A lot of principles and bases throughout these years have opened up multiple possibilities for a DC2 setup. This makes DC2 worth exploring.

Modified Core Duration

Polyphasic Society’s original DC2

This scheduling variant was proposed by Polyphasic Society.

  • It gives an extra amount of sleep reduction compared to the standard variant. Totaling 4h40m of sleep, this version may be more appealing to adapt to than the standard version
  • This DC2 variant has a similar amount of total sleep to E3 (3.5h core and 3 20m naps). This is also comparable to the similar total sleep between E2 and DC1, the first schedules in the Everyman and Dual Core lines. 
  • The basis of this version was to induce a bit more sleep reduction in the first core sleep and add a second nap.

Notes on 2.5-hour Core

However, beginners should not schedule a 2.5h core from the beginning; it likely will result in heavy SWS wakes and increase the chance for oversleeping. As mentioned above, there is still some chance for the automatic reduction in the SWS core’s length after adaptation. Thus, it is not necessary to adapt to this variant.

This total sleep may also contribute to the potential inflexibility of the schedule after adaptation; flexing each sleep block will be very challenging. Moreover, throughout the years, there were virtually no successful adaptations to this DC2 variant. It may still benefit sleepers with lower SWS requirements or shorter overall sleep duration on monophasic sleep, though.

80-minute cycle compression

Similar to the Polyphasic Society’s proposal of a possible Dual Core 2 variant, this DC2 variant stresses on the final goal once the adaptation is complete. The premise is to compress both core sleeps down to a multiple of 80m cycles (from 90m).

The common approach would be to adapt to the original 3-1.5 standard combination first. Then, wait for the compression to occur, thanks to the frequency of sleep. It is still not ideal to start an adaptation with this variant, however; SWS/REM wakes will only occur more frequently. More sleep inertia will increase the chance to oversleep.

Same duration for both cores

This variant offers a somewhat higher total sleep than usual, but not high enough to belong to the extended category. Both core sleeps last for 2.5h each. So far there has only been one success with this variant, however.

The objective is to provide some buffer total sleep to advance to DUCAMAYL with both flexible cores. This example sets the consideration for appropriate core durations to make sure they can receive some flexibility after adaptation.

Because of the highly uncommon and ill-advised 2.5h core duration, beginners and inexperienced polyphasic sleepers should avoid this variant. An easier way to schedule a similar amount of sleep duration for both cores is to have a 3.5h core and a 1.5h core respectively.

  • The 3.5h core duration is very popular in E3 over the years. It also has a lot of successful adaptations along the way.
  • The purpose is to make use of the potential +30m from the 3h mark for more REM sleep. Nevertheless, the seemingly better statistically likely REM period is oftentimes a 5h core.
  • Once adaptation is complete, it may become more comfortable to flex both core sleeps.


DC2 with a Pronap
  • This interesting Dual Core 2 variant rotates the whole schedule to earlier hours.
  • Most sleep blocks move to night hours, and there is only 1 daytime nap. As a result, the wake gap between each core is possibly smaller than that on the standard version.
  • The first nap is at the usual position of the second core; and as a result, it is very similar to an Everyman schedule.
  • The first core likely will cover most SWS needs, while the second core may be a mixed core (containing both SWS and REM).
  • Both naps may contain REM sleep, which can boost the chance to recall dreams.

The Pronap does the following:

  • It can provide more REM sleep for individuals with somewhat higher REM requirements. The first nap is located in REM peak, which will be full of REM sleep. The reason a Pronap can be useful is that both core sleeps mostly cover all SWS needs. This leaves basically no room for SWS to occur in this hypothetical Pronap.
  • It may become flexible after adaptation.

However, it is important to note that this is a new, untested proposal for an alternate DC2 variation. There is also little incentive to try out this early rotation/Pronap variant, though. The first core is too early in the evening and becomes a liability for social time.


Extension of the first core
Extension of the second core

Dual Core 2-extended simply extends one of the cores by a full cycle, making it 3h total. This variant shares the same total sleep as E2-extended, with the exception of having 2 core sleeps.

The only advantages of this version are:

  • The first core can be delayed to the last hours of SWS peak; this means it is possible to schedule this core at 11 PM or later.
  • People with high sleep requirements (especially in both REM and SWS) can make use of the sleep frequency and the assistance from naps to meet the necessary vital sleep requirements.

However, while looking realistic on paper, DC2-extended has rarely reported any successes. It is also inferior to E2-extended, which is more convenient in scheduling. E2-extended also reports more success and has an allegedly easier adaptation.

While it is possible to schedule the first core to be 4.5h long and the second core to be 1.5h long (for more SWS recovery from intense exercising or high SWS requirement), DC2-extended also seems eclipsed by DC1-extended.

  • It has the same total sleep for both cores combined while only requiring 1 daytime nap.
  • The longer wake period between the only nap and the cores makes the nap easier to schedule around events. 

Lifestyle Considerations


In spite of the seemingly unnecessary sleep distribution across the day on Dual Core 2, it is actually viable to attempt this schedule.

A standard day on Dual Core 2
  • DC2 can become flexible after adaptation and can fit into a lot of lifestyles.
  • The first nap can be during a noon or lunch break (which is possible in many workplaces).
  • The second nap can be after work (~4:30-5:30 PM). It is then possible to sustain 2 naps per day, with a consistent work schedules on weekdays for example.
  • Both core sleeps total at least 3 full sleep cycles; with the more efficient use of sleep peaks, DC2 is an underrated option to pick for some physical exercises.
  • The second core, being safe from virtually any real-life interruptions at late hours, acts as a storage for REM sleep. This can boost alertness and performance before heading out to work or school. In addition, once adapted, it can create a strong impression of a long, restful night sleep that compacts down to only 90m sleep.

Not only are REM sleep requirements safer on DC2 (compared to regular E3) but also the DC2 naps can sustain alertness after only a couple hours staying awake.

The naps replenish the energy budget after a long morning at work/school and then another nap after work/school for extra recovery. This also indicates that DC2 is one of the few polyphasic schedules that can go well with mainstream 9-to-5 jobs as long as it is possible to take one nap in the middle of this work gap.


However, DC2 is not without faults.

  • It can be tricky to plan the nap before lunch when the noon break window is too short. One may have to either take the nap and skip lunch, or vice versa. 
  • In addition, many people can only sustain 1 daytime nap in the long run, so 2 naps may prove to be too difficult to keep up. This also calls for the viability of the early rotation/Pronap scheduling choice, at the cost of a complete sacrifice of social time in the evening.
  • The first core sleep of DC2 (which usually starts around ~9-10 PM, or at worst, 11 PM in rare cases) poses more hindrance for social life around these hours; extended versions mitigate this weakness, but they are also outperformed by other better extended schedules.
  • Non-natural Segmented sleepers or poor planning during the night gap can quickly incite boredom and boost the difficulty of the adaptation.

Overall, even though DC2 displays the flaws of a typical Dual Core schedule, it does offer decent variability and diversity in its scheduling potential.

Main author: GeneralNguyen
Page last updated: 8 April 2021