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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 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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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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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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* 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-->