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{{TNT|Segmented}}

{{TNT|Segmented}}

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Segmented is a [[Special:MyLanguage/biphasic|biphasic]] [[Special:MyLanguage/Template:Polyphasic Sleep Schedules|schedule]]<ref>[https://www.polyphasic.net/schedules/biphasic/ polyphasic.net]. Retrieved 23-11-2020.</ref> with two [[Special:MyLanguage/cores|cores]] at night, usually with a total sleep time close to one's personal [[Special:MyLanguage/monophasic|monophasic]] baseline.   

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.   

==Origin== <!--T:2-->

==Origin== <!--T:2-->

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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>https://onlinelibrary.wiley.com/doi/abs/10.1111/j.1365-2869.1992.tb00019.x</ref>.  

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" />.

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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 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.

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.

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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.

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.

{{further|Dual core|Alternative mechanism}}

{{further|Dual core#Alternative mechanism}}

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The wake gap between each core (known as "core gap") should 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.  

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.  

 

== Adaptation== <!--T:9-->

== 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. The second core sleep containing much REM sleep can also result in grogginess or dizziness upon waking. Over time, with strict adherence to the schedule, these issues should disappear.  

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.

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.

==Difficulty== <!--T:12-->

==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.  

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== <!--T:14-->

==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.

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 === <!--T:16-->

=== 6-hour total sleep === <!--T:16-->

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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.

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=== <!--T:20-->

===Extended/Non-reducing=== <!--T:20-->

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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.

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=== <!--T:22-->

===Uneven core lengths=== <!--T:22-->

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[[File:Segmented Uneven.png|right|thumb|A Segmented variant with uneven core lengths]]

[[File:Segmented Uneven.png|right|thumb|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 <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.

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.

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=== <!--T:25-->

===Late first core=== <!--T:25-->

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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.  

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

===Siesta-hybrid=== <!--T:28-->

===Siesta-hybrid=== <!--T:28-->

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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.  

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=== <!--T:35-->

===Night shift=== <!--T:35-->

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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.

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== <!--T:38-->

==Lifestyle Considerations== <!--T:38-->

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* Vivid dreaming experiences have been reported on the schedule over the years, most of which come from the second core.

* Vivid dreaming experiences have been reported on the schedule over the years, most of which come from the second core.

== References == <!--T:46-->

== References == <!--T:46-->

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<references />{{TNT|Polyphasic Sleep Schedules}}

<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>

{{TNT|Polyphasic Sleep Schedules}}

[[Category:Schedules]]

[[Category:Schedules]]

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