Difference between revisions of "Segmented"

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<languages />{{Segmented}}
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A [[biphasic]] [[Template:Polyphasic Sleep Schedules|schedule]], which contains two [[cores]] at night, usually with a high total sleep time, close to a personal [[monophasic]] baseline.
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{{TNT|Segmented}}
== Mechanism ==
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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 [https://www.ncbi.nlm.nih.gov/pmc/articles/PMC4763365/ 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 [https://onlinelibrary.wiley.com/doi/abs/10.1111/j.1365-2869.1992.tb00019.x 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.
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Segmented is a [[Special:MyLanguage/biphasic|biphasic]] [[Special:MyLanguage/Template:Polyphasic Sleep Schedules|schedule]] with two [[Special:MyLanguage/cores|cores]] at night, usually with a total sleep time close to one's personal [[Special:MyLanguage/monophasic|monophasic]] baseline.
  
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 <u>some potential sleep reduction</u> 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.
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==Origin== <!--T:2-->
  
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.
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Segmented sleep, sometimes referred to as bifurcated or divided sleep, is one of the original polyphasic sleep patterns. It is the basis of the [[Special:MyLanguage/Dual core|Dual core]] schedule line. In its non-reducing form, it is believed to have been practiced by some human societies since time immemorial until the advent of electric lighting . In short photoperiods (fewer daylight hours), it has been shown that human sleep is naturally segmented<ref name="wehr" />.
  
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.
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==Adaptation Difficulty==
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People would often go to bed some time after sunset, wake up after a few hours, stay awake for a couple hours, and then go back to bed until sunrise. Some naturally Segmented sleepers report interrupted monophasic sleep, where they wake up in the middle of the night. They are often suggested to adopt a Segmented sleep schedule.
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.
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==Mechanism== <!--T:5-->
  
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.
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==Alternate Variants==
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The [[Special:MyLanguage/Polyphasic Discord|Polyphasic Discord Community]] has discovered some possible mechanics of Segmented sleep. The basis of Segmented sleep is the sleep peaks. During the early hours of the night (~21-24), when natural melatonin secretion starts, SWS can be gained efficiently. In EEG readings of adapted sleepers, the first core sleep is usually dense in [[wikipedia:Slow-wave_sleep|SWS]], whereas the second core sleep contains  primarily [[wikipedia:Rapid_eye_movement_sleep|REM]] sleep. The divided core sleeps are thus denser in vital sleep stages, and allow for a small cut in total sleep with stable sleep times. Naps in the day are often not required due to segmented's longer cores perserving light sleep in addition to the the nightly core gap reducing the amount of time awake between the cores during the day.
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.
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===Slightly shortened core sleeps===
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<gallery mode="packed-overlay" widths="200" heights="200">
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Both core sleeps are scheduled to be 3.5 hours by default. The sleep cycles likely lengthen to about 105 minutes from the approximately 90-minute cycles on monophasic sleep. This would also explain the viability of the schedule despite having fewer cycles. However, recently EEG readings of some members have shown the opposite.
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{{further|Dual core#Alternative mechanism}}
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The wake gap between each core (known as "core gap") should be at least 90 minutes, with a longer gap recommended (~2.5-3 hours) for non-natural Segmented sleepers. The reason for this is to prevent the cores from becoming [[Special:MyLanguage/interrupted sleep|interrupted sleep]] and to prevent the difficulties with falling asleep or being productive enough.
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== Adaptation== <!--T:9-->
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For naturally Segmented sleepers, adaptation is easy. For non-natural Segmented sleepers, adapting to Segmented may be harder than adapting to [[Special:MyLanguage/Siesta|Siesta]] or [[Special:MyLanguage/E1|E1]]. Waking up from the first core could be difficult. Boredom during the night gap can make it hard to stay awake. Over time, with strict adherence to the schedule, these issues should disappear.
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After Segmented, there is a gradual adaptation route to [[Special:MyLanguage/Dual core|Dual core]] schedules, and also [[Special:MyLanguage/Triphasic|Triphasic]], as the division of core sleeps had been learned.
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==Difficulty== <!--T:12-->
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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 for beginners.  
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==Variants== <!--T:14-->
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While the default dual 3.5 hour core variant has had the most success, a few other combinations are also feasible and have been adapted to in the past. Beginners can attempt these variants, with some precautions.
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=== 6-hour total sleep === <!--T:16-->
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<gallery mode="packed-overlay" widths="250" heights="250">
 
File:Segmented short 1.png|Segmented with 6h total sleep (Version 1)
 
File:Segmented short 1.png|Segmented with 6h total sleep (Version 1)
 
File:Segmented short 2.png|Segmented with 6h total sleep (Version 2)
 
File:Segmented short 2.png|Segmented with 6h total sleep (Version 2)
</gallery>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.
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These are 2 modified variants that have reported some success over the years. Since the total sleep is only 6 hours, it may be suitable for those with slightly below average monophasic baselines (~7h). One problem with this schedule would be a circadian dip in the early afternoon hours, without naps to address them. Because more light sleep has been cut compared to the default variant, staying awake could be more difficult.
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The wake gap between each core should be at least 4 hours to cover the SWS and REM peaks more efficiently, as well as to reduce the length of the day gap. The overall adaptation may be more difficult than the standard version because of reduced sleep time. The benefit is the added extra time at night, and only needing to sleep at night without daytime naps.
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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 needing similar amounts of REM and SWS can pick the latter. Overall, the 3-3 variant better balances sleep stages, and has seen more success overall than the 4.5-1.5 variant.
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===Extended/Non-reducing=== <!--T:20-->
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{{further|Non-reducing#Segmented}}
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It is also possible to extend this schedule, possibly to the point that it does not cut any sleep from one's monophasic baseline. This allows for an easy adaptation, while still gaining some of the benefits from Segmented sleep. These schedules may also benefit those with higher sleep needs (~9h on monophasic), younger sleepers, and those who regularly perform intense exercise.
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===Uneven core lengths=== <!--T:22-->
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[[File:Segmented Uneven.png|right|thumb|A Segmented variant with uneven core lengths]]
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This variant, which is rarely attempted, has cores of slightly different lengths. These variants allows for slightly more time awake, may be easier to schedule, without a significantly harder adaptation. Other plausible combinations include <u>3-3.5</u>, or even <u>4.5-2.5</u> and <u>5-1.5</u>. It would be helpful to know the [[wikipedia:Slow-wave_sleep|SWS]] and REM requirements before picking any of these variants, though.
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Generally, variants with a longer first core allows for more alertness during core gap, and the second core does not need to be as long. However, the longer the first core, the less "DC-like" it becomes, meaning that the sleep stages becomes less distinctly allocated into the two cores. The longer first core may also resemble Siesta, with the second sleep looking like a daytime core sleep.
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===Late first core=== <!--T:25-->
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[[File:Segmented Late First Core.png|right|thumb|Segmented with a late first core]]
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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. This variant is not usually recommended, as the first core being away from SWS peak drastically increases the difficulty. Circadian management is recommended, as with other late-core schedules.
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For this variant, the core gap can be smaller than the default, because of the higher SWS pressure prior to core 2.
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===Siesta-hybrid=== <!--T:28-->
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[[File:Segmented Siesta-hybrid.png|right|thumb|A Segmented that looks like Siesta sleep]]
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The idea behind this variant is similar to Siesta, but with both cores at night, and with the short core providing much of the SWS. Sleepers with lower SWS requirements or want to sleep less around evening hours can attempt this variant.
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This variant has recorded at least 2 successes; one attempt was 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 much longer to compensate. Similar ideas can apply to 2.5-4.5 core distribution or so.
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The main issue with this is that it is impossible for an average sleeper (90m SWS need) to gain all the needed SWS in the first core, the second core will have to provide the remaining SWS, and pushing the second core to late hours of the night may increase the difficulty of the process.
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Similar to the default schedule, this variant also takes away some of the social time in the evening in exchange for time in the core gap.
  
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.
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[[File:Siesta-hybrid.png|right|thumb|Segmented-Siesta hybrid]]
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Alternatively, Segmented may be scheduled with one core at night and another core in the day. Only a few successes have been reported thus far. This variant looks like Siesta with a long daytime core, and both core sleeps miss the peaks. The dark period should be 2-3h before the night core, and continue for ~2h after it to stabilize the circadian rhythm.  
  
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.
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===Uneven core durations===
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Adaptations to this would be much more difficult than a regular Segmented schedule, because skipping both sleep peaks can greatly hinder sleep quality. Over the course of adaptation, staying awake during the graveyard and morning hours will be tough, and having a long sleep in the day may disrupt the circadian rhythm.  
[[File:Segmented Uneven.png|center|thumb|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 <u>3-3.5</u>, or even <u>4.5-2.5</u> and <u>5-1.5</u>. 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.
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===Night shift=== <!--T:35-->
===Late first core===
 
[[File:Segmented Late First Core.png|center|thumb|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.
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{{Segmented-ext}}
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[[File:Shift Work.png|right|thumb|A Variant for Third Shift]]
===Extended/Non-reducing===
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The idea of this is to have both core sleeps after before work. Alternatively, the daytime core can be earlier so that it is shortly after work. Little is known about this scheduling variant, and adaptations have been overall unsuccessful, due to the large circadian rhythm shift it requires.  
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.
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There have been several failed attempts Segmented sleep for shift work. This is expected, as overall rates of success are very low for shift workers.
  
===Siesta-hybrid===
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==Lifestyle Considerations== <!--T:38-->
[[File:Segmented Siesta-hybrid.png|center|thumb|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.[[File:Siesta-hybrid.png|center|thumb|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.
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===Third shift===
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Segmented, which allows for a range of schedule options, can be suitable for many. It greatly benefits those who naturally wake up during the night, and also allows those who are unable to take a daytime nap to still sleep polyphasically.
[[File:Shift Work.png|center|thumb|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:
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*'''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.
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Before one transitions to Segmented, it is important to plan what to do during the core gap. Staying awake with few things to do  while everyone else is sleeping can be difficult. For naturally segmented sleepers, this is less of a problem. Here are a few tips:
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* Make a list of what activities or tasks that are well suited to being done during the night. This includes entertainment! Being alone can also be an advantage at times. Be sure to consider that these hours must be in [[Special:MyLanguage/dark period|dark period]], in which you will be wearing [[Special:MyLanguage/Dark_period#Goggles|goggles]], and as such will not be able to differentiate colors.
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* Dedicate time for self-care. The core gap can be useful for relaxation after long days at work. Self-care can include autogenic training, [[Special:MyLanguage/meditation|meditation]], [[Special:MyLanguage/yoga|yoga]], and stretching. Note that it may be unadvisable to do these things when you are having problems staying awake.
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* Plan for your day. People often have a lot to work on and care about. No matter how much extra awake time you might have, time management is always important.
  
*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.
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Advantages of Segmented over other schedules include:
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* Segmented is the only schedule that easily allows >12h of continuous wake time without needing any naps. This can allow many people who are unable to take naps to sleep polyphasically.  
  
*'''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.
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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.
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* Segmented offers a relatively high amount tst (total sleep time). It is viable to schedule the first core later than normal, ~23, to allow evening events. The only thing to note, though, is that a late first core likely will delay the end of the second core, and may interfere with your morning activities. Under normal scheduling, however, there will be more limited evening social time on Segmented sleep.
  
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.
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* Segmented can become somewhat flexible after adaptation. Some experienced sleepers have reported being able to flex at least one of the core sleeps. Being able to flex the core sleeps allows for more freedom in controlling the length of core gap to suit one's schedule. For example, on days with little to do, the core gap can shrink down a bit, so that the second core can start earlier than usual, or vice versa. When sudden events occur that would require skipping sleep, Segmented also allows relatively fast recovery afterwards.  
  
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 <u>a party night</u>, 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.
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* Segmented sleep, especially the extended variant with a longer first core, can support intense physical exercise.
  
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.
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* Vivid dreaming experiences have been reported on the schedule over the years, most of which come from the second core.
  
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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== References == <!--T:46-->
  
In spite of all the powerful advantages, Segmented seems at a disadvantage compared to other biphasic schedules when attempted by underage individuals, mostly those who are not natural Segmented sleepers. It may be possible that these individuals are better off with a long, continuous core sleep rather than segmented core sleeps, which can be a reason for quite a few incomplete adaptations.  
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<ref name="wehr">{{cite journal |vauthors=Wehr TA |date=1992 |title=In short photoperiods, human sleep is biphasic |journal=Journal of Sleep Research |volume=1 |issue=2 |pages=103-107 |doi=10.1111/j.1365-2869.1992.tb00019.x}}</ref>
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{{TNT|Polyphasic Sleep Schedules}}
 
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Latest revision as of 10:42, 4 January 2021

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Segmented
Segmented
chart link

Total sleep7 hours
Proposed byNone, used by humans throughout history.
DifficultyModerate
Specification2 long cores at night aligned to SWS and REM peaks respectively.

Segmented is a biphasic schedule with two cores at night, usually with a total sleep time close to one's personal monophasic baseline.

Origin

Segmented sleep, sometimes referred to as bifurcated or divided sleep, is one of the original polyphasic sleep patterns. It is the basis of the Dual core schedule line. In its non-reducing form, it is believed to have been practiced by some human societies since time immemorial until the advent of electric lighting . In short photoperiods (fewer daylight hours), it has been shown that human sleep is naturally segmented[1].

People would often go to bed some time after sunset, wake up after a few hours, stay awake for a couple hours, and then go back to bed until sunrise. Some naturally Segmented sleepers report interrupted monophasic sleep, where they wake up in the middle of the night. They are often suggested to adopt a Segmented sleep schedule.

Mechanism

The Polyphasic Discord Community has discovered some possible mechanics of Segmented sleep. The basis of Segmented sleep is the sleep peaks. During the early hours of the night (~21-24), when natural melatonin secretion starts, SWS can be gained efficiently. In EEG readings of adapted sleepers, the first core sleep is usually dense in SWS, whereas the second core sleep contains primarily REM sleep. The divided core sleeps are thus denser in vital sleep stages, and allow for a small cut in total sleep with stable sleep times. Naps in the day are often not required due to segmented's longer cores perserving light sleep in addition to the the nightly core gap reducing the amount of time awake between the cores during the day.

Both core sleeps are scheduled to be 3.5 hours by default. The sleep cycles likely lengthen to about 105 minutes from the approximately 90-minute cycles on monophasic sleep. This would also explain the viability of the schedule despite having fewer cycles. However, recently EEG readings of some members have shown the opposite.

The wake gap between each core (known as "core gap") should be at least 90 minutes, with a longer gap recommended (~2.5-3 hours) for non-natural Segmented sleepers. The reason for this is to prevent the cores from becoming interrupted sleep and to prevent the difficulties with falling asleep or being productive enough.

Adaptation

For naturally Segmented sleepers, adaptation is easy. For non-natural Segmented sleepers, adapting to Segmented may be harder than adapting to Siesta or E1. Waking up from the first core could be difficult. Boredom during the night gap can make it hard to stay awake. Over time, with strict adherence to the schedule, these issues should disappear.

After Segmented, there is a gradual adaptation route to Dual core schedules, and also Triphasic, as the division of core sleeps had been learned.

Difficulty

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 for beginners.

Variants

While the default dual 3.5 hour core variant has had the most success, a few other combinations are also feasible and have been adapted to in the past. Beginners can attempt these variants, with some precautions.

6-hour total sleep

These are 2 modified variants that have reported some success over the years. Since the total sleep is only 6 hours, it may be suitable for those with slightly below average monophasic baselines (~7h). One problem with this schedule would be a circadian dip in the early afternoon hours, without naps to address them. Because more light sleep has been cut compared to the default variant, staying awake could be more difficult.

The wake gap between each core should be at least 4 hours to cover the SWS and REM peaks more efficiently, as well as to reduce the length of the day gap. The overall adaptation may be more difficult than the standard version because of reduced sleep time. The benefit is the added extra time at night, and only needing to sleep at night without daytime naps.

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 needing similar amounts of REM and SWS can pick the latter. Overall, the 3-3 variant better balances sleep stages, and has seen more success overall than the 4.5-1.5 variant.

Extended/Non-reducing

It is also possible to extend this schedule, possibly to the point that it does not cut any sleep from one's monophasic baseline. This allows for an easy adaptation, while still gaining some of the benefits from Segmented sleep. These schedules may also benefit those with higher sleep needs (~9h on monophasic), younger sleepers, and those who regularly perform intense exercise.

Uneven core lengths

A Segmented variant with uneven core lengths

This variant, which is rarely attempted, has cores of slightly different lengths. These variants allows for slightly more time awake, may be easier to schedule, without a significantly harder adaptation. Other plausible 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 allows for more alertness during core gap, and the second core does not need to be as long. However, the longer the first core, the less "DC-like" it becomes, meaning that the sleep stages becomes less distinctly allocated into the two cores. The longer first core may also resemble Siesta, with the second sleep looking like a daytime core sleep.

Late first core

Segmented with a late first core

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. This variant is not usually recommended, as the first core being away from SWS peak drastically increases the difficulty. Circadian management is recommended, as with other late-core schedules.

For this variant, the core gap can be smaller than the default, because of the higher SWS pressure prior to core 2.

Siesta-hybrid

A Segmented that looks like Siesta sleep

The idea behind this variant is similar to Siesta, but with both cores at night, and with the short core providing much of the SWS. Sleepers with lower SWS requirements or want to sleep less around evening hours can attempt this variant.

This variant has recorded at least 2 successes; one attempt was 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 much longer to compensate. Similar ideas can apply to 2.5-4.5 core distribution or so.

The main issue with this is that it is impossible for an average sleeper (90m SWS need) to gain all the needed SWS in the first core, the second core will have to provide the remaining SWS, and pushing the second core to late hours of the night may increase the difficulty of the process.

Similar to the default schedule, this variant also takes away some of the social time in the evening in exchange for time in the core gap.

Segmented-Siesta hybrid

Alternatively, Segmented may be scheduled with one core at night and another core in the day. Only a few successes have been reported thus far. This variant looks like Siesta with a long daytime core, and both core sleeps miss the peaks. The dark period should be 2-3h before the night core, and continue for ~2h after it to stabilize the circadian rhythm.

Adaptations to this would be much more difficult than a regular Segmented schedule, because skipping both sleep peaks can greatly hinder sleep quality. Over the course of adaptation, staying awake during the graveyard and morning hours will be tough, and having a long sleep in the day may disrupt the circadian rhythm.

Night shift

A Variant for Third Shift

The idea of this is to have both core sleeps after before work. Alternatively, the daytime core can be earlier so that it is shortly after work. Little is known about this scheduling variant, and adaptations have been overall unsuccessful, due to the large circadian rhythm shift it requires.

There have been several failed attempts Segmented sleep for shift work. This is expected, as overall rates of success are very low for shift workers.

Lifestyle Considerations

Segmented, which allows for a range of schedule options, can be suitable for many. It greatly benefits those who naturally wake up during the night, and also allows those who are unable to take a daytime nap to still sleep polyphasically.

Before one transitions to Segmented, it is important to plan what to do during the core gap. Staying awake with few things to do while everyone else is sleeping can be difficult. For naturally segmented sleepers, this is less of a problem. Here are a few tips:

  • Make a list of what activities or tasks that are well suited to being done during the night. This includes entertainment! Being alone can also be an advantage at times. Be sure to consider that these hours must be in dark period, in which you will be wearing goggles, and as such will not be able to differentiate colors.
  • Dedicate time for self-care. The core gap can be useful for relaxation after long days at work. Self-care can include autogenic training, meditation, yoga, and stretching. Note that it may be unadvisable to do these things when you are having problems staying awake.
  • Plan for your day. People often have a lot to work on and care about. No matter how much extra awake time you might have, time management is always important.

Advantages of Segmented over other schedules include:

  • Segmented is the only schedule that easily allows >12h of continuous wake time without needing any naps. This can allow many people who are unable to take naps to sleep polyphasically.
  • Segmented offers a relatively high amount tst (total sleep time). It is viable to schedule the first core later than normal, ~23, to allow evening events. The only thing to note, though, is that a late first core likely will delay the end of the second core, and may interfere with your morning activities. Under normal scheduling, however, there will be more limited evening social time on Segmented sleep.
  • Segmented can become somewhat flexible after adaptation. Some experienced sleepers have reported being able to flex at least one of the core sleeps. Being able to flex the core sleeps allows for more freedom in controlling the length of core gap to suit one's schedule. For example, on days with little to do, the core gap can shrink down a bit, so that the second core can start earlier than usual, or vice versa. When sudden events occur that would require skipping sleep, Segmented also allows relatively fast recovery afterwards.
  • Segmented sleep, especially the extended variant with a longer first core, can support intense physical exercise.
  • Vivid dreaming experiences have been reported on the schedule over the years, most of which come from the second core.

References

  1. Wehr TA (1992). "In short photoperiods, human sleep is biphasic". Journal of Sleep Research. 1 (2): 103–107. doi:10.1111/j.1365-2869.1992.tb00019.x.