TC1

Tri Core 1, or TC1, is one of the newer version of Triphasic sleep and was created in 2017 with the goal to neutralize the inconvenient daytime core on Triphasic sleep. On TC1, all core sleeps are moved to the night hours since sleep pressure at night is often higher than in the day, and the short daytime nap resembles a short siesta, filling up the alertness level with a long daytime wake gap from the third to the first core. There have been few successes on TC1 than on Triphasic because of TC1's somewhat inconvenient structure of night sleep.

Triphasic

Tri Core 1
chart link Legend   Sleep   Dark period   Flexible sleep window
Total sleep	4 hours 50 minutes
Proposed by	Polyphasic Sleep Discord Community
Difficulty	Hard
Specification	3 single-cycle core sleeps, plus one nap.

Mechanism

The main difference between Triphasic and TC1 is the addition of a daytime nap and a core that is placed in the middle of the other 2 cores located at SWS and REM peak respectively. As a result, the adaptation to TC1 will be different from Triphasic. Initially, it will be difficult to fall asleep in the core sleeps because they are placed 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 deemed easier than on Triphasic when adapting. 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 and 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 to avoid interrupted sleep.

The daytime nap alleviates homeostatic pressure by providing a chance to get more REM sleep, and sustains alertness until the SWS core. However, the repartitioning process on TC1 is no less than, if not more difficult, than on Triphasic, due to the ease of oversleeping in any of the core sleeps when adapting. Because a lot of sleep types go into the core, SWS deprivation may not be the worst to experience on the schedule.

After adapting to TC1, one can then slowly transition to DC3 by turning the third core into a nap and adding a third nap in the afternoon (~4 PM).

Lifestyle considerations

The defining distinction between Triphasic and TC1 is that the night gap is a lot more packed on TC1 with the core sleeps. This can create an impression that TC1 divides the day into several small parts with each core giving more and more compressed vital sleep stages. However, because the wake gap at night is shorter on TC1 than on Triphasic, physically lighter and more peaceful activities are preferred on TC1 (e.g, studying, cooking, planning, chores) to assist in falling asleep in the cores. However, for many individuals, it may be very inconvenient to schedule 3 core sleeps at night, when all of them are placed 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, also because of its total sleep. Slightly flexing a core sleep or two, and/or the nap is acceptable, but so far no one has demonstrated how flexible TC1 can be, assuming a normal sleep requirement.

It is also possible to extend one TC1's core by an extra 90 m cycle, but so far no one has adapted to this extended variant either, and it is largely outclassed by Triphasic-extended in scheduling convenience and viability. However, TC1 still offers a large amount of sleep reduction (with a difficult adaptation) and can be a fitting choice for those who love Triphasic, or the idea of having 3 core sleeps, but cannot afford any core sleeps during the day.

Polyphasic Sleep Schedules Scheduling overview Biphasic E1 Extended Siesta Segmented BiphasicX Everyman E2 Extended E3 Extended E4 Extended E5 Sevamayl Trimaxion Dual core DC1 Extended DC2 Extended DC3 DC4 Bimaxion Tri core Triphasic TC1 TC2 Nap only Uberman Dymaxion Tesla Spamayl Experimental QC0 Ducamayl Camayl Hypothetical Non-polyphasic Monophasic Random