Segmented

A biphasic schedule, which contains two cores at night, usually with a high total sleep time, close to a personal monophasic baseline. <translate>

Segmented

Segmented
chart link Legend   Sleep   Dark period   Flexible sleep window
Total sleep	7 hours
Proposed by	None, used by humans throughout history.
Difficulty	Moderate
Specification	2 long cores at night aligned to SWS and REM peaks respectively.

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Mechanism

Segmented sleep, sometimes referred to as Bifurcated sleep, is one of the earliest polyphasic schedules. It is also one of the 4 Biphasic schedules available. Aside from its role as the progenitor of Dual Core sleep, its creation (non-reducing) was natural and dated back to the preindustrial era (1750-1850), making it roughly 250 years old as of today. In short photoperiods (less daytime hours and more night time hours), it was researched that human sleep is also naturally segmented. What is commonly observed in this Segmented behavior is that people would often go to bed after sunset, wake up after some hours at night, stay awake for a couple hours, and then go back to bed until sunrise hours. Segmented sleep is still common nowadays, being involuntarily or voluntarily practiced by many in the world. Nowadays, naturally Segmented sleepers have a short wake gap between 2 cores (~1.5-3h) as a result of interrupted monophasic sleep, in the middle of the night. It only makes sense then, that sleepers would wake up feeling refreshed from the first core, do something at night, before they go back to sleep when sleepiness level rises enough.

Currently, the Polyphasic Discord Community has discovered more sleep mechanics regarding Segmented sleep. For starters, Segmented is one of the 5 schedules with only core sleeps (2) and no naps. The entire basis of Segmented sleep is constructed based on the sleep peaks. It is widely regarded that the early hours of the night (~9-10 PM, SWS peak), when natural melatonin secretion is kickstarted, quality SWS will largely benefit if sleep time begins around these hours. Throughout a lot of EEG readings of adapted sleepers, it is commonly seen that the first core sleep is highly SWS-oriented, while the second core sleep, being near sunrise hours (~6-9 AM, REM peak), has a strong propensity for densely populated REM sleep. However, on Segmented it is worth noting that some minor amount of REM sleep can still be present in the first core sleep, and the same for SWS in the second core. The segmentation of the main monophasic core sleep into 2 core sleeps that align with the sleep peaks bolster the sleep quality with much deeper core sleeps, and allow for some potential sleep reduction with strict bedtime everyday. Since 2 core sleeps are already allocated to night hours (which is similar to monophasic sleep's distribution of sleep), no naps in the day are needed, because the amount of light sleep from both cores is sufficient to sustain wakefulness for the entire day.

Even though it may look odd that both core sleeps last for 3.5h rather than the would-be 3h, or 4.5h, it was later explained that each core consists of 2 full sleep cycles plus an extra 30 minutes of sleep time to cover the statistically likely REM period (just like 5h and 6.5h core). The statistically likely REM period originates from Polyphasic Society, and the evidence for it is very poor (eight monophasic readings). While its existence is questionable, it is still possible to see the effects from having the cores be 3.5 hours long. Another explanation for the 30m extension on each core is from the possibility that the cycles extend to roughly 105m as compared to the standard 90m cycles in monophasic sleep. This would explain the viability of the schedule despite having fewer cycles.

The wake gap between each core should be at least 90m, and even more (~2.5-3h) for non-natural Segmented sleepers to ease the adaptation. The first thing is to avoid the interrupted sleep issue. Interrupted monophasic sleep often occurs when there is a only a brief period of awakening during sleep, before the sleeper goes back to sleep. Staying awake for at least ~90m will separate the interruption and create an entirely new sleep architecture for the second core. Should the wake gap be too short, it will be unproductive to do different activities and it may be difficult to fall asleep in the second core as sleep pressure is not high enough to induce sleep. Some people have quit Segmented with a 2h gap because of the inability to adapt or feeling too unproductive during these short night gap.

Adaptation Difficulty

Before attempting this schedule, it is important to look over all Biphasic patterns to choose if Segmented sleep is worth the choice. For naturally Segmented sleepers, the adaptation is basically complete if they already have a long exposure to the core-split mechanics. For non-natural Segmented sleepers, adapting to Segmented is potentially more challenging than to a biphasic pattern with a long, uninterrupted core sleep at night, such as Siesta and E1. It is still possible to adapt to Segmented, but initially waking up from the first core can pose common issues (e.g, heavy sleep inertia, boredom during the night gap). The second core sleep, being replete with REM sleep, can cause certain amounts of sleep inertia, grogginess or even slight dizziness upon waking up, due to the effects of the dense eye-movement activities from REM sleep. Over time, with enough consistency, these issues will no longer persist, and waking up will be invigorating from each sleep. However, compared to naturally Segmented sleepers, there can still be certain glimpses of mild unproductivity during the night gap after adaptation, and it may require an extended amount of time on the schedule to fully enjoy the night gap.

Thus, the difficulty level of Segmented varies across individuals, and depends on the amount of sleep being scheduled. Overall, it is still considered a friendly schedule to begin sleeping polyphasically, as total sleep is among the highest of all schedules. While potentially not as popular as Siesta and E1, it does promise several niches that completely set it apart from its Biphasic counterparts. This will be discussed in the Lifestyle Considerations section.

Once Segmented is adapted to, one then then proceed to a Dual Core, or even Triphasic schedule, following the habit of segmenting the main night sleep into 2 smaller core sleeps.

Alternate Variants

While the standard 3.5-3.5 core combination has brought about a lot of successes in the community, multiple other core combinations are also viable and have been succeeded on their own right. With proper consideration, polyphasic beginners can attempt these variants, with some precautions and recommendations at hand.

Slightly shortened core sleeps

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  Segmented with 6h total sleep (Version 1)

• 

  Segmented with 6h total sleep (Version 2)

These are 2 possible modified variants that have reported some success over the years. Since the total sleep is only 6 hours, it would be more suited for people with slightly reduced monophasic duration/requirements (e.g, 7-7.5h). The danger when adapting to this schedule would be the tiredness periods around the circadian nadir (noon-early afternoon hours) while there are no naps on the schedule. Because more light sleep has to be sacrificed compared to the 7h version, less wakefulness sustainer is provided by either of these variants.

The wake gap between each core can be at least 4h to cover more hours of each corresponding sleep peak, to get in more quality sleep. The overall adaptation may be more difficult than on the standard version (for average sleepers) because of the reduced sleep time. The benefit is the added extra time, and having to sleep only twice per day, abusing the increased waking hours in the day without having to add any naps. If adapted, these variants would be one of the best way to enjoy Segmented sleep.

The difference between 4.5-1.5 and 3-3 core distribution is that those with more SWS requirements can attempt the former option, while those with more REM sleep and a reasonable amount of SWS requirements can pick the latter. Overall, the 3-3 variant gives a better balance for each sleep stage, and has some slight advantage in adaptation success compared to the other variant. Both of these variants, however, follow the 90m -cycle rule in scheduling.

Uneven core durations

A Segmented variant with uneven core lengths

This is one of the many variants whose core durations are not equal to each other. Excluding the 4.5-1.5 variant from the previous section, here either core can be slightly longer or shorter than the other, and total sleep hovers around ~6.5-7h. The advantage of these variants is to salvage a bit more extra wake time than the original version, while essentially not increasing the adaptation difficulty by a lot. There is very rare success with these types of scheduling, however. Other viable combinations include 3-3.5, or even 4.5-2.5 and 5-1.5. It would be helpful to know the SWS and REM requirements before picking any of these variants, though.

Generally, variants with a longer first core can help with sustaining alertness better through the graveyard hours between 2 cores, and the second core does not need to be as long. However, the longer the first core, the less distinct its sleep architecture will become. What this means is that a longer first core (e.g, 4.5-5h core) will contain more REM sleep alongside the abundant SWS, and the second core will contain a less percentage of REM sleep. The longer first core also gives the impression of Siesta sleep, with the second sleep looking like a daytime core sleep.

Late first core

Segmented with a late first core

Even though it is initially deemed unrealistic and even impossible to schedule this segmented variant, over the years there have been a success or two. Sleepers who would schedule this variant are expected to have low SWS needs, and/or a lot of polyphasic experience as well as the stringent management of food, exercise and lighting. Since the first core is shifted out of the SWS peak entirely, it is necessary to employ various methods to ensure a sufficient amount of SWS, especially when coupled with heavy exercising. Similar to the previous options, multiple core combinations can be applied in this scheduling scheme.

There are, however, a lot of hefty benefits from this type of variant. For one, social time in the evening is secured, because sleep time is not as early as the standard version. For another, the wake gap between 2 cores can be smaller than the original version, because of a potentially higher SWS pressure that will be resolved in the second core sleep. This setup would also benefit those who can wake up at later hours in the evening with a shifted work schedule to late morning or later. A somewhat short sleeper would even benefit from this variant more - not only is sleep time reduced somewhat, but all the access to evening events like other monophasic individuals and an uninterrupted flow of daytime commitments, without needing any naps. Adaptation to this variant is expected to be very difficult, which is one important note to bear in mind.

Extension/Non-reducing

Non-reducing Segmented

Segmented-extended

The slight difference between Segmented-extended and non-reducing Segmented is that the former can still contribute to some amount of sleep reduction (e.g, 9h monophasic sleeper), while the latter does not reduce any sleep (e.g, 4.5-4.5 core combo for 9h sleeper). Either variants, however, only report some success over the years. The non-reducing variant has achieved a lot of success since the preindustrial era, which brings up the point that segmented sleep can be a natural sleep pattern for humans. Nowadays, with the advent of blue light and certain difficulties in managing the schedule alongside social time and hassling evening hours, it is deemed a lot harder to adapt to either variant. Another downside of both variants is that the longer core sleeps plus the wake gap between 2 cores makes the second core end later than usual. This can then clash with morning commitments if one has to wake up earlier than expected.

A benefit from the non-reducing variant is that it potentially can allow for some flexibility of either core during adaptation, and naturally segmented sleepers can still adapt to the schedule if they habitually wake up during the night and simply go to bed when they are tired enough. One success from the non-reducing variant (~7h total sleep on average) has the first core being ~4.5h long consistently (3 full cycles) while the second core hovers around 2h on average (~1.5-2.5h depending on day). This suggests that non-reducing variants can still be utilized by short sleepers to achieve a very flexible Segmented scheduling with natural Segmented habits to great effects. For non-natural Segmented sleepers, it is still advisable to try to sleep at the same time everyday for each core sleep. Regardless, not reducing total sleep may make it more difficult to adapt, because of the overall lower sleep pressure than a reducing variant.

Siesta-hybrid

A Segmented that looks like Siesta sleep

This variant has surprisingly recorded at least 2 successes over time up to date; one attempt was done in a winter, where photoperiod was short. The first core becomes a lot shorter than usual, being reduced all the way to only 1 cycle, while the second core is dramatically longer than usual to compensate for the first core. Similar ideas can apply to 2.5-4.5 core distribution or so. The idea behind this variant is to have a very long wake gap between each core so that the second core can still occupy a fair amount of REM peak hours while still giving out sufficient SWS. The main concern is that since it is impossible for an average sleeper with at least 90m SWS to meet all SWS in the first core, the second core will have to provide the remaining SWS, and pushing the second core to very late hours at night may increase the difficulty of the process. Sleepers with lower SWS requirements or want to sleep less around evening hours can attempt this variant. However, as with a very unorthodox scheduling and the excessively long dark period, it will be tricky to make this Segmented variant work. This variant also takes away most, if not all social time in the evening; social time will have to be traded with the long wake gap between cores depending on personal preference.

Segmented-Siesta hybrid

Alternatively, Segmented can be scheduled with one core at night and one core in the day. Only a success or two have been reported thus far. This variant looks like Siesta with a long daytime core, and both core sleeps miss out on the peaks. The dark period should be 2-3h before the night core, and continue for ~2h after this core to stabilize the circadian rhythm. Adaptations are rare and a lot more difficult than a regular Segmented schedule, because skipping both sleep peaks can greatly hinder quality sleep. Over the course of adaptation, staying awake during the graveyard and morning hours will be tough, and having a long sleep in the day immediately can shake up the current sleep habits, if they are very different from this scheduling (e.g, regular 7-8h monophasic exclusively at night, non-nappers). The personal sleep peaks may change with artificial melatonin onset as a result of this new Segmented habits, however this entrainment will likely require an extended period of time for the circadian rhythm to be completely rotated.

Third shift

A Variant for Third Shift

Very little is known about this scheduling method, and adaptations have been overall not rewarding. The nature of third shift often brings about changes in many health aspects, including higher risks for cardiovascular diseases, increased stress, lowered immune system and hypertension in the long run, including a monophasic pattern. Adapting to a Segmented pattern without the natural habit will result in a very risky adaptation. There have been at least a couple failures while deploying Segmented sleep for shift work, however, success is very rare, only a case or two. The idea is to have a core sleep right after the work period, and a core sleep before work. The plan on paper sounds compelling, but the adaptation process is far from easy.

Lifestyle Considerations

Given the extremely versatile ways of scheduling Segmented, there is a reason that Segmented sleep remains popular nowadays and has been succeeded by many polyphasic sleepers, from the most basic beginners to the most experienced veterans. A lot of brand new polyphasic sleepers often reflect on their inability to sleep in one chunk on monophasic sleep, and perpetually wake up in the middle of the night. The perfect solution would then be to start a Segmented adaptation as a result of the abrupt awakening. Thus, Segmented sleep would greatly benefit these groups of population.

Before one transitions to Segmented, it is very important to plan ahead what to do during the wake gap between 2 cores. This is very important because it is a critical component that can sway the adaptation to one's favor, should they know how to utilize the waking hours here. It is true that staying awake lonely at night when everyone else is sleeping and especially having nothing interesting to do can quickly become a daunting task to stay awake for many hours straight. For naturally segmented sleepers, this is not a big problem, but for non-segmented sleepers, there are a few tips to optimize these hours:

• Make a list of what activities or tasks that can only be achieved at night time or much better done at night than in the day. Take advantage of the silence of the night. This includes entertainment activities (e.g, watching TV shows), studying (after the first core) to revise the learned materials prior to the first core. Entertainment is fair game if you have not had a chance to enjoy them properly for a while. Being alone can also be an advantage at times.

• Dedicate to self-care. Self-care involves a lot of things, and it’s always a good thing to look after yourself when you have been too tired from working and committing to other obligations in the daytime. Self-care is also a great way to relieve built-up stress and anxiety. Autogenic training, meditation, yoga and stretching all come to mind. Just a brief session of 30-45m will help. Self-care isn’t something exclusive to Dual Core sleep - it can be utilized on any polyphasic schedules as well.

• Plan your next day or day(s). Planning activities is often the activity that takes the most amount of time if you fully craft out what you have to do in the day. In the roles of CEOs, managers and probably even interns and students, you will have a lot to work on and be concerned about. With clear planning comes clear execution of tasks - the worst thing of being on a polyphasic schedule is not being able to utilize the promising extra waking hours you gain from your hard-work adaptation. Thus, time management is key and if you think hard enough, I don’t think you run out of things to do.

In addition, there are massive advantages of Segmented that set it apart from other biphasic schedules. First, there is no need for a nap during the day. This effectively enthrones Segmented as the only schedule that can support more than 12h continuously staying awake without having to lie down for any shuteyes. In the modern society, this is an insurmountable perk that other polyphasic schedules cannot match. The seemingly endless wake gap allows for planning of several social events, even activisms, or any mainstream jobs that do not allow for any naps in the day. This is a fantastic way to adapt to Segmented sleep and enjoy the long daytime wake gap just like any monophasic sleepers.

Second, since Segmented does offer a decent amount of sleep, it is very viable to schedule the first core at ~11-11:30 PM (dark period begins at approximately 10 PM) to schedule a bit more evening events without having to sleep too early. The only thing to note, is that the late first core likely will delay the start time of the second core, so it is important to look at the second core and see if it will interfere with indispensable morning commitments. Under normal scheduling, however, there will be more limited evening social time on Segmented sleep.

Third, Segmented sleep can become flexible after adaptation. However, the flexibility records of Segmented is more humble than those of E1. Certain experienced sleepers or sleepers who go through a moderately challenging/easy adaptation to Segmented have shown their ability to flex at least one core sleep. Being able to flex the core sleeps allows for the absolute freedom in controlling the amount of waking hours between each core to suit one's schedule depending on days. For example, on certain days with nothing much to do, the core gap can shrink down a bit, so that the second core can start earlier than usual. Likewise, if there are more required tasks that need to be completed during this wake gap, the second core can be delayed a bit, or the first core can start earlier than usual. Lastly, the resilience of Segmented sleep also allows it to absorb some damages in scheduling, such as a party night, by delaying the first core to after the party and starting the second core some time after that. After adaptation, it should not take long to recover from such abrupt changes in sleep times, as long as these do not happen too often.

Fourth, Segmented sleep can support a lot of physical exercises, although like other schedules, it can be burdensome to keep the intense exercising habits while adapting. This can be remedied by having a longer first core and a shorter second core to increase the mobility of SWS gain. After the adaptation is complete, exercise intensity can increase again to match the previous level.

Lastly, the second core sleep on Segmented is often safe from real life interruptions and is often considered a REM stock for lucid dreaming. A lot of vivid dreaming experiences have been reported on the schedule over the years, most of which come from this second core. As an added bonus, this core (often long enough), can fix some inconsistencies or hiccups in sleep quality from the first core (e.g, interruptions in the middle, higher sleep onset than usual).

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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

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