Tri Core 1

A standard TC1

Tri Core 1, or TC1, is the second polyphasic schedule in the Tri Core family of schedules. Being a multi-core schedule, it sports 3 core sleeps. However, it now has 1 daytime nap; all core sleeps also concentrate around nighttime hours. With a total sleep still below 5h each day, TC1 is a rather difficult schedule to adapt to. 


  1. Mechanism
  2. Adaptation
  3. Alternate Variants
  4. Lifestyle Considerations


Tri Core 1 now has a core in the middle of the night (~2-3 AM); this core is between the SWS peak and REM peak cores. Each of these core sleeps also gives a different distribution of vital sleep stages.

  • The first core will be very dense with SWS.
  • The second core will be mixed between SWS and some amount of REM sleep.
  • The third core will heavily favor REM sleep.
  • The wake gap between each core should be at least 2h to facilitate falling asleep in each core. A somewhat longer wake period also helps avoid interrupted sleep.
  • The daytime nap alleviates homeostatic pressure by providing some more REM sleep. This assists alertness until the SWS core. Because 3 core sleeps only total 4.5h sleep, a daytime nap becomes essential for the long daytime wake period.
  • The wake gap from the nap to the SWS peak core is ideally ~7-7.5h long, and should not exceed 8h. One can also stay awake for ideally ~6-7h from the REM peak core to the nap. 
  • TC1’s adaptation seems to favor natural Segmented sleepers. The wake gap between each Segmented core is also 3h, similar to those on TC1.

The further segmentation of core sleeps around night hours on TC1 is similar to that on Dual Core schedules. For this reason, TC1 is more or less a compounded Dual Core schedule. The main difference is 2 wake periods at night, which can give the impression of a long night.

TC1 is also a polyphasic schedule that has a strong preference for night sleep; this in return limits daytime sleep as much as possible. With this purpose, TC1 improves the inconvenient daytime core on Triphasic. 


Cold turkey

Cold turkey is a viable approach. However, it is not without any downsides, especially for non-natural Segmented sleepers. 

  • Initially, it will be difficult to fall asleep in the core sleeps because they are close to each other.
  • SWS will start to get into the core sleeps, resulting in a slowly building REM debt.
  • However, because there are 3 core sleeps around night hours, staying awake until the next core sleep is likely easier than on Triphasic.
  • The repartitioning process on Tri Core 1 is no less than, if not more difficult, than on Triphasic; oversleeping can occur in any cores, especially the mixed core. Because a lot of sleep types go into the core, SWS deprivation may not be the worst to experience on the schedule.

Gradual adaptation

Transition from Segmented sleep

A gradual adaptation from Segmented or DC1 seems viable. This is to entrain the habitual nocturnal awakening habit before adapting to TC1. 

  • DC1 will retain the daytime napping habit. The nap on DC1 should be at the same spot as that on the desired TC1 version. 
  • Segmented is not as difficult a first adaptation step as DC1. However, there is no daytime nap to learn. 
  • Either Segmented or DC1 should have the same start time for the SWS core, 10 PM in the example above. Then, the first core of Segmented breaks down into 2 smaller cores, with the addition of a nap for Tri Core 1. 

Despite a potentially easier transition with this method, most of the notes of the cold turkey method also apply here. The changes in sleep architecture with the addition of a third core sleep will require good management of sleep cues. 

After adapting to TC1, one can then slowly transition to DC3 by turning the third core into a nap. Then proceed to add a third nap in the afternoon (~4 PM). More data is necessary to determine what other variants of TC1 would be possible to adapt. 

Alternate Variants

Over the years, there has only been success with the standard variant. This makes sense because of the overshadowed versions that TC1 may have.

  • Extending any of the core sleeps will only bring more inconvenience with scheduling the cores.
  1. Specifically, it may be very difficult to fall asleep in at least one core, given the already narrow wake gap.
  2. With this distribution of sleep, Triphasic-extended would be better, with many adaptation successes.
  • Flipping the sole nap’s position with any of the cores will only increase adaptation difficulty. This is because nighttime hours favor core placement rather than short naps. 
  • Swapping positions of the third core with the nap is only more inconvenient with the long daytime sleep. 

Lifestyle Considerations

Research on lifestyle

Looking for a research paper on Tri Core 1? Look here!

Differences from Triphasic

The defining distinction between Triphasic and Tri Core 1 is that the night gap is a lot more packed on TC1 with the core sleeps. One should also note the following when adapting to TC1:

Typical activities during night gap on TC1
  • Because the wake gap at night is shorter on TC1 than on Triphasic, physically lighter and more peaceful activities are preferable on TC1 to assist in falling asleep in the cores. Such activities include, but not limited to: studying, cooking, planning, chores and meditation.
  • To many individuals, it may be very inconvenient to schedule 3 core sleeps at night, when all of them are so close to one another.
  • Strenuous exercising may also be overbearing for the total sleep of less than 5 hours. It is also very unlikely TC1 will become very flexible after the adaptation because of its total sleep. Slightly flexing a core sleep or the nap is acceptable, but so far no adapted sleepers have demonstrated how flexible TC1 can be.
  • Heavy insomniacs who cannot sleep for more than few hours in a row at night can attempt TC1. The core structure looks similar to an augmented Segmented schedule. Being unable to sleep for more than an hour or two is an exploitable niche for TC1 adaptation. The wake periods between the cores can now leave room for other activities rather than rolling around and trying to sleep. The wake periods are also short enough to maintain the alertness levels throughout the night. 

Other scheduling notes

While it is also possible to extend one TC1’s core by an extra 90m cycle, so far no one has adapted to this extended variant either. As said earlier, it is largely outclassed by Triphasic-extended in scheduling convenience and viability.

The core in SWS peak is not doing evening social time any good, either. However, TC1 still offers a large amount of sleep reduction. It can therefore be a fitting choice for those who love Triphasic, or the idea of having 3 core sleeps but no daytime core sleeps.

Main author: GeneralNguyen

Page last updated: 3 April 2021