DC2

DC2

Dual Core 2
chart link Legend   Sleep   Dark period   Flexible sleep window
Total sleep	5 hours 10 minutes
Proposed by	Polyphasic Society
Difficulty	Moderate
Specification	1 dusk core, 1 dawn core, 2 daytime naps

Dual Core 2, or DC2, is the second Dual core schedule, with two cores and two naps. The total sleep of DC2 is around 5 to 5.5 hours.

Mechanism

With 2 core sleeps placed around the peaks and 2 naps in the day, DC2 is similar to E3-extended in timings, except that the first nap of E3 is replaced with a core.

The first core should ideally contain nearly all the required SWS, while the second core should contain primarily REM sleep. The naps help sustain wakefulness with reduced total sleep time, and may or may not contain REM sleep.

The total sleep is relatively high, and may allow for flexing after adaptation. Compared to E2, which has a similar total sleep, the split cores may allow for more efficient sleep. Four sleeps per day keeps sleep pressure relatively low, and skipping naps would be more tolerable compared to schedules like E2, as long as this does not happen often.

Difficulty

For non-naturally segmented sleepers, adapting to Dual core schedules generally more difficult compared to Everyman, because splitting of vital sleep stages into two cores may induce difficult wakes. In that case, adapting to DC2 is slightly more difficult compared to E2, but may be easier for naturally segmented sleepers.

Adaptation

Either cold turkey or gradual adaptation to DC2 is possible. After adapting to DC2, one can start flexing the naps and possibly core(s) and adapt to DUCAMAYL, or transition to DC3. The first core sleep may also naturally shorten to about 2.5h as a result of compressed repartitioning and high frequency of sleep.

Lifestyle Considerations

In spite of the four scheduled sleeps, DC2 can be a viable schedule for many, because of its ability to become flexible after adaptation. The first nap can be taken during a noon or lunch break and the second nap can be taken after work (16-17:30). It is then possible to sustain 2 naps per day, with a consistent work schedules on weekdays for example.

DC2 also allows for some physical exercise since it has a relatively high total time in cores. Both cores may feel long and restful after adaptation, despite the relatively short durations compared to monophasic sleep. DC2 provides many alertness boosts, replenishing energy in the morning, at noon, and in the afternoon.

However, it may be difficult to both take a nap and have lunch with a relatively short lunch break. As with other Dual core schedules, the first core starts relatively early, and may pose difficulties with social life. Non-natural segmented sleepers may experience boredom during the night gap, which can make adaptation more difficult.

Variants

Over the years, many variants of this schedule has been proposed following a range of scheduling principles. This opens up a wide range of scheduling options for DC2, which may suit different people.

Shortened core(s)

A DC2 variant proposed by Polyphasic Society

The inner ring is the original variant of the schedule proposed by Polyphasic Society, which cuts more sleep than the current standard variant. Totaling 4h40m of sleep, this version has a similar amount of total sleep to E3 (3.5-hour core). However, scheduling a 2.5h first core may result in heavy SWS wakes in the beginning and cause oversleeping. This reduced total sleep may also make this variant less flexible after adaptation. Throughout the years, this variant has seen little success, but those with slightly reduced monophasic sleep requirements may be able to adapt to it more easily.

It may also be possible to compress the cycle lengths down to 80 minutes. The common approach would be to adapt to the standard variant, and then wait for the compression to occur. It is not recommended to directly start an adaptation to variant.

A DC2-modified variant with the same sleep duration for both cores

Equal core lengths

This DC2 variant offers slightly more time in cores, with both core sleeps being 2.5 hours. Only one success has been documented with this variant so far, however. This schedule prepares one for DUCAMAYL, in which both cores are flexible. Because of the 2.5h core duration, beginners should avoid this variant.

An easier way to schedule a similar amount of sleep duration for both cores is to have 3.5h and 1.5h cores, both of which being more common core lengths. Once adaptation is complete, it may also be possible flex both core sleeps.

Early rotation/pronap

A DC2 variant with the first nap around dawn

This variant rotates the whole schedule backward to earlier hours. The goal of this is to place 3 sleep blocks at night, leaving only one nap in the day. As a result, the core gap is also shorter. The first nap is placed at the usual position of the second core, resembling an Everyman schedule. The first core will likely cover most of the SWS, while the second core may be mixed (containing both SWS and REM, but likely more REM sleep). Both naps are more likely to contain REM sleep, which can boost dream recall.

In this variant the first nap can also be extended to become a pronap (30-40m) to better sustain wakefulness and provide more REM sleep. However, this variant has not been tested, with the obvious issue of the early first core conflicting with social time for most people.

Extended

A DC2-extended variant

The second core can be extended to a 3h sleep. 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. The only advantage of this version is that the first core can be delayed to the last hours of SWS peak - meaning it is possible to schedule this core at 11 PM or later. However, while looking realistic on paper, DC2-extended has never really reported any successes. It is also outclassed by E2-extended, which is more convenient in scheduling, more success and 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 is also shadowed by DC1-extended, which has the same total sleep for both cores combined while only requiring 1 daytime nap (more comfortable to keep up long-term).

A DC2 variant with TC1 structure

TC1-alike

This is an experimental variant, proposed by Sekvanto. Both cores have the same length of 2 hours. Three blocks of sleep are placed during the night hours: both cores and one of the naps. The second nap is placed midday. Such schedule resembles the structure of TC1, replacing one of the cores with a nap and extending the remaining cores. This variant has fewer naps during the daytime, which potentially makes it more convenient socially for some. An early core may be an issue, on the other hand. Another benefit is a dawn nap, which may increase dream recall.

It should be noted that 2h cores are usually considered a bad choice since they are a bit longer than an average sleep cycle, which makes SWS wakes more possible. This schedule overall isn't popular and had only a couple of successful adaptations. However, 2h cores work for some, supposedly either by having extended sleep cycles or by getting more light sleep at the end of the cores.

References

Polyphasic Sleep Schedules Scheduling overview Biphasic E1 Extended Siesta Segmented BiphasicX Everyman E2 Extended E3 Extended E4 Extended E5 Sevamayl Trimaxion Dual core DC1 Extended DC2 Extended DC3 DC4 Bimaxion Tri core Triphasic TC1 TC2 Nap only Uberman Dymaxion Tesla Spamayl Experimental QC0 Ducamayl Camayl Hypothetical Non-polyphasic Monophasic Random