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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 [https://en.wikipedia.org/wiki/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.

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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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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[[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 [https://en.wikipedia.org/wiki/Slow-wave_sleep 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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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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<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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