DC3
Mechanism
Dual Core 3, or DC3, is the third dual core schedule, following the sequence of the Dual Core family with further sleep reduction in both core sleeps, both of which now only have 1 full cycle, with the addition of the nap around sunrise hours. The total sleep of the whole schedule is 4h, which is also the bare minimum sleep threshold that an average person (~8h monophasic) should be able to adapt to.
The core sleep in the SWS peak as usual will heavily favor SWS, while the second core sleep will contain some more SWS and invite some REM sleep as well. The primary reason is that the first core will not be able to cover all SWS requirements (assuming ~90m SWS need each day) and the second core will be required to complete the task. Given the low total sleep, to ensure quality SWS, the first core always has to lie within the SWS peak. The remaining naps, being in the daytime hours will most definitely store a lot of REM sleep to support sufficient REM baseline, ideally. However, the last nap, located in mid-afternoon hours (~4 PM), may not always guarantee REM sleep. REM sleep will hugely be accumulated in the first nap around dawn, which will generate a lot of vivid and intense dreaming when adapting.
Nonetheless, because the longest sleep block on the schedule is only 90 minutes long, DC3 is one of the most difficult polyphasic schedules to adapt to. Even though it has a high frequency of sleep (5 sleeps per day), waking up after only 90 minutes of sleep around graveyard hours makes SWS and/or intense REM wakes very frequent during adaptation. With SWS deprivation symptoms being present until an equilibrium and healthy amount of SWS is obtained, oversleeping can occur in any sleep blocks, especially the core sleeps. Even when the wake gap between each sleep seems to be short, staying awake during graveyard hours during adaptation is going to be a major task, when sleep inertia from the repartitioning cores can prove to be overwhelming.
In order to schedule DC3 effectively, both core sleeps will have to be moved closer together to avoid as much daytime sleep as possible; this will limit the number of daytime naps to 2 per day (noon & afternoon). So far, the default variant is the variant that reported some successes; adaptations to DC3 are very rare due to the more sophisticated split-sleep mechanics of a Dual Core schedule, and it is largely overshadowed by Everyman 3 (E3), especially the variant with a 3.5h core sleep.
Difficulty Scale
DC3 is also one of the 3 schedules whose original design would provide only 4 hours of sleep each day. The other 2 schedules in the same category of minimum sleep threshold for adaptability are E3 and Bimaxion, an easier equivalent of Dymaxion. It is generally agreed on that DC3 is a lot harder than E3, due to the number of rare adaptations and how many days each polyphasic adapter lasts on this schedule before forfeiting their attempt. Compared to Bimaxion, it may be equal in terms of difficulty, which is already formidable for any polyphasic beginners barring sleep mutants with a low monophasic baseline. One niche of the cold turkey adaptation is that non-nappers will be able to learn to nap effectively faster than on schedules with fewer naps or higher amount of sleep; this is owing to the immense sleep pressure from the schedule that builds up swiftly.
However, DC3-extended, despite its troublesome scheduling of sleeps, has reported one success in 2020, effectively suggesting that the concepts and design of DC3 are still hospitable for adaptation. The extension of a core sleep on this version facilitates a much more challenging would-be adaptation on the regular DC3 version.
Adaptation Methods
Polyphasic sleepers can start an adaptation to TC2 and then slowly transition to DC3 (rhythmic preservation, using the same number of sleep blocks on each schedule and change a core into a nap), although this path will take a very long time to achieve for both steps. Alternatively, a gradual adaptation from DC2 or DC1 also looks viable, but so far there are no known successes with this method. Starting the schedule cold turkey (from monophasic) has reported at least one successful adaptation (in the case of a sleep mutant). Regardless of the adaptation pathways, sleepers would eventually need to go through the intensified repartitioning of vital sleep stages to be able to finally adapt to the regular DC3 setup.
Alternate Variants
Since there are only few adaptations to DC3, there are only few respective scheduling variants should one decide on DC3 for the high frequency of sleep, which can boost alertness around the clock with the dense number of naps.
Extended versions:
This extended version has a long core sleeps and boosts the total sleep to 7h each day. It has recorded one successful adaptation from the Discord community. There is only a 90m wake gap in between 2 cores, but because the sleeper was a well-entrained segmented sleeper, the short wake gap posed no problems during adaptation. This small wake gap is also dedicated to praying, which does not require several hours staying awake like on other Dual Core schedules. Despite the inconvenient scheduling, it is possible to adapt to this variant with an appropriate lifestyle and certain personal motivations.
Version 2 has a more realistic setup than the first version, with a reasonable amount of total sleep and can handle the sleep onset issues better during adaptation than the first version. Over the years it has reported one success or so, mostly because of the intrusiveness of the sleep blocks. If scheduling is possible, the wake gap between 2 cores can be used for more activities and the distribution of sleeps can make for a comfortable adaptation, where skipping a nap on this variant during adaptation should not do as much damage as on the standard version. However, it is recommended that beginners should pursue E3-extended instead, with the same amount of sleep, much higher success rate and more beneficial scheduling.
Lifestyle Considerations
Because DC3 possesses all the features of Dual Core sleep, the lifestyles that apply to the previous DC schedules can somewhat apply to DC3. The wake gap at night can be dedicated to religious activities (e.g, praying), studying or planning depending on how long it is. Because of a lot of sleep blocks each day, it is necessary to schedule food and other commitments carefully before attempting this schedule. Only flexible, work-from-home occupations can benefit from this schedule - working at one's own pace in a familiar environment is more relaxing and less demanding than under constant supervision of a boss or a high-ranking member at the office; the amount of sleep deprivation can be insurmountable and can damage a lot of productivity hours when adapting in a more stressful and rigorous environment (e.g, jobs that require constant vigilance, high focus or sharp mental concentration around the clock, having to nap at a noisy workplace or in public, or evening events). In addition, with only 4 hours of sleep, intense exercising may not be suitable as the recovery process may not suffice with increased SWS requirements. Sickness and injury, which can result in excessive sleep, may also break the patterns of the schedule even with the adapted state.
It is also unlikely DC3 will be flexible after adaptation due to its low total sleep. With the distribution of sleeps across a lot of usually socially busy hours, DC3 is more of a short-term polyphasic schedule with a lot of naps for more opportunities of vivid dreaming. Being overshadowed by its counterparts E3 and even E3-extended, DC3 generally has limited viability for any long-term consideration, with all aspects considered.
