Naturally Segmented Sleepers


Are you a naturally segmented sleeper? This is whether you frequently wake up in the middle of the night without any explanation. Have you read every single sleep hygiene tip in the book to no avail? Well, since you are surfing the internet and trying to find a unique solution that works for you, have you ever thought of embracing it?

Natural Segmented sleep

You might be what is called a “naturally segmented sleeper”, or a “natural dual core sleeper”.


Before the industrial revolution, the common sleep pattern for people was to split their night sleep into two portions, as detailed in Roger Ekirch’s book “At Day’s Close: Night in Times Past1. Basically, people would wake up in the middle of the night to chat, pray, have sex etc. This all changed once the industrial revolution arrived, however.

People were forced to work long days and simply did not have time to sleep in two blocks. Additionally, the industrial revolution brought artificial lighting, which disrupted the circadian rhythm. This is observable in people who extend their dark period to 14 hours. It causes human sleep to naturally revert back to the old habit of sleeping in two segments2.

Why am I Experiencing This Phenomenon in the Modern World?

There may be several different reasons why you are waking up during the middle of the night. These are the most common reasons:

  • Not using a dark period3
  • Following an irregular sleep schedule4
  • Pain
  • Sleep apnea
  • Digestive issues
  • Suffering from Alzheimer’s disease.
  • Drinking too much fluid during the day.
  • Anxiety-issues.

If you have already tried fixing your situation, these above-mentioned reasons will not be applicable to you. There should be two options remaining, though.

  • A failed polyphasic sleep adaptation caused you to become naturally segmented
  • You were naturally segmented ever since you were young.

Original Findings by the Community

According to a survey done in the Discord on segmented sleep habits (n = 39), out of the 24 people who had attempted a split core schedule and then abandoned it:

  • 3 people were naturally segmented sleepers before they started sleeping polyphasically.
  • 6 people awoke their naturally segmented sleep habits after attempting a polyphasic sleep schedule.
    • 4 of these people chose to continue sleeping in a segmented pattern voluntarily.
    • 2 of these people were forced to continue sleeping in a segmented pattern involuntarily.
  • 8 people continued to experience intermittent wakes after leaving their polyphasic schedule, but these only lasted for a short time. people did not suffer these effects and were simply able to return to their monophasic schedule.

From these findings, it is clear that a rather significant portion of people (25% in this survey) are going to awaken some naturally segmented habits after attempting a Dual core-style schedule.

Naturally Segmented for As Long As I Remember

In addition, a more fundamental reason for your sleep habits is because you are still prone to the old sleeping pattern of humans. Because of this, we refer to you as a naturally segmented sleeper. If this is the first time you have given a thought about your condition and have not tried to cure it in any way, this may not be appropriate to you.

This better suits individuals who are not able to find a way to fix their situation.

Choosing an Appropriate Polyphasic Schedule

Determining Criteria

If you are a naturally segmented sleeper, you have probably suffered from a naturally segmented sleep pattern since you were a kid or a teenager. However, this can be rough if you feel like you cannot control your sleep. Yet, there are ways to fix your anxiety. The optimal way to “treat” your condition is to accept that you will be waking up in the middle of the night and actually start doing it voluntarily.

  • There are several polyphasic sleep schedules that utilize core sleep interruptions to improve your sleep efficiency.
  • If you wake up after 3 to 6 hours, schedules from the Dual Core group will be good for you.
  • If you are waking up after only around 2 to 3 hours, look into the Tri Core schedule group.
  • Otherwise, If you wake up after a longer time, you can use these schedules with a longer first core. Examples include Everyman 3-extended, Everyman 2, etc. 


The initial goal is to secure your mental health.

  • Start adapting to one of these schedules with a total sleep time of roughly 5 hours.
  • After that, you can further optimize the duration you sleep with a gradual adaptation method.
  • If 5 hours of sleep sounds too scary, Segmented or Dual core 1-extended are also good options. This is the case if the sleep disturbance occurs after around 2 sleep cycles.
  • Quad Core 0 offers a good alternative if the intermittent wake occurs after only 1 sleep cycle.

Adapting to a polyphasic sleep schedule should undoubtedly help you establish control in your life. You can learn more about adaptations here.

Polyphasic Experience of Naturally Segmented People

To learn more about what naturally segmented sleepers feel about following a polyphasic sleep schedule, check out the interview with Jace, who is a naturally segmented person. She has successfully adapted to at least two polyphasic sleep schedules.

Natural Segmented Sleep After Adaptation Failure

After failing an adaptation to a Dual Core schedule, you try to sleep for a full 8 hours. However, you are no longer able to do it and you wake up after 3 hours. This continues day after day and you wake up energized in the middle of the night. It does not even matter when you have an alarm early in the day. Thus, you accumulate a lot of sleep deprivation. Your naturally segmented tendencies have awoken from this sleep habit.

NOTE: Some people have short periods of disturbed sleep after failing a polyphasic sleep schedule. However, these issues will often eventually fix themselves.

If you are unhappy with being stuck on a Dual core schedule, you can un-learn the naturally segmented tendencies. Nevertheless, your naturally segmented tendencies awoke for a reason. As long as you conquer your anxiety, you should be able to function better on a segmented schedule than on a monophasic schedule.

Regardless, it’s possible to transition back to a monophasic sleep schedule. This is going to be hard, but possible. Up until now, you have tricked your body into suppressing its naturally segmented tendencies. Thus, you can teach your body to do it again.

The Sleep Box: Sleep Restriction

Getting rid of intermittent wakes, or WASO during sleep requires the utilization of the sleep box method. It serves to restrict the time you spend in bed until your sleep onset shortens and your body has to abandon the interruptions to get enough sleep.

  • Drastically reduce your total bed time (TBT) to 3 to 5 hours.
  • After rigorously sticking to your new schedule for a few weeks (until the intermittent wake is gone), gradually increase the TBT up to your usual monophasic sleep time.
  • The gradual element is pivotal, since large jumps in TBT may cause the intermittent wakes to return.
Week TBT (hours) Comment
0 – 2 3 Tiredness increases, intermittent wakes   still persist
3 3 Intermittent wakes gone
4 5 Intermittent wakes still gone
5 7 Intermittent wakes still gone
6 8 Intermittent wakes still gone, goal achieved

Table 1. Example of using the sleep box method to fix the sleep disturbances

As an alternative, it is also possible to follow an Everyman schedule to achieve the same effect, which may be mentally easier for you.

  • This is because you will be able to nap during the day, which alleviates tiredness.
  • If you choose to go that route, be sure to stick to your schedule extremely rigorously. When you want to re-stabilize your sleep, adhering to the schedule is absolutely mandatory.


What is the best method of handling the naturally segmented sleep style? Should you try to fix it or accept it? There are arguments for both sides, and it depends on what you prefer. Although, following a split core schedule will permit you to achieve a higher productivity and a more holistically beneficial lifestyle. Therefore, if you have the opportunity to do so, consider switching over to a split-core schedule to maximize your personal quality of life.

Main author: Crimson

Page last updated: 20 January 2021


  1. Ekirch, A. R. (2006). At day’s close: night in times past. WW Norton & Company.
  2. Wehr, T. A. (1992). In short photoperiods, human sleep is biphasic. Journal of Sleep Research, 1(2), 103-107. [PubMed]
  3. Green, A., Cohen-Zion, M., Haim, A., & Dagan, Y. (2017). Evening light exposure from computer screens disrupts sleep, biological rhythms and attention abilities. Sleep Medicine, 40, e117-e118. [PubMed]
  4. Lee, Da-Hye, et al. “Sleep irregularity in the previous week influences the first-night effect in polysomnographic studies.” Psychiatry investigation 13.2 (2016): 203.