From Polyphasic Sleep Wiki
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Total sleep~7-9 hours (non-reducing, so depends on individual monophasic sleep need)
Proposed byGeneralNguyen
SpecificationMainly 1 core and 1 nap. Sometimes more cores/naps can be used to reduce total sleep. Both cores and naps are flexible.
Former namesPrototype X, Experimental X

BiphasicX is a non-reducing flexible biphasic schedule,[1] which does not reduce total sleep time compared to a personal monophasic baseline and heavily depends on natural individual sleep tendencies and a stable circadian rhythm.


This schedule is named to differentiate itself from other established biphasic patterns (Siesta, Segmented and E1). The suffix "X" is meant to denote variability in the daytime nap duration, which does not have to be the same every day.

Despite biphasic sleep patterns being common in humans, the schedule did not have any documented adaptations until early 2020. The first detailed report was written by a user after 45 days on the schedule. A follow-up was additionally submitted about 20 days after the first report. Afterwards, the schedule has seen numerous attempts, with many of which being successful.


This flexible biphasic schedule contains 2 sleeps per day, without reducing asleep. For example, a person who needs 8 hours of sleep each day can have a 6-hour core sleep at night and 2-hour core sleep during the day, in a manner resembling Siesta.

Many may find themselves naturally biphasic sleepers with a main core sleep at night that covers most of their vital sleep needs, complemented with a nap or short core during the day depending on how sleepy they are. Night sleep is the primary focus of the schedule, while the daytime sleep that fits the circadian energy dip in the early afternoon. Alternatively, others may have tendencies toward Segmented-like sleep, which two cores of similar lengths at night separated by a wake gap in between.

Short naps on the schedule contain mainly light sleep, whereas longer sleep blocks also contain SWS and REM sleep. Any type of sleep would aid in memory and learning with the alertness boost they provide. On this schedule, the length of the daytime sleep block need not be fixed, and can vary depending on one's level of tiredness in that particular day. Despite the flexibility, sleeping late in the evening should be avoided, as it may interfere with the core sleep at night.


Adaptation should start by scheduling fixed lengths for both the nighttime and the daytime sleeps, such as with one of the extended variants of Siesta or E1, or with an intermediate day nap length (40-70 minutes). However, sleep times can be slightly different on a day-to-day basis, even during adaptation.

Over time, by sleeping twice per day, the sleeper should become accustomed to biphasic sleeping, being able to wake up from both the core sleep and daytime nap without using any alarms even without strict timings. Total sleep time will also become consistent with only small variations from day to day.


Unlike adaptation to reducing schedules, adaptation to BiphasicX does not involve intense sleep deprivation since repartitioning of vital sleep is not required. The adaptation to this schedule is therefore expected to be much easier than any adaptation to reducing schedules, to the extent that it should not noticeably affect cognitive performance.

Lifestyle Considerations

The schedule fits many normal lifestyles that allow daytime naps, even with slightly inconsistent times. A consistent dark period is needed to stabilize the circadian rhythm.

On busier days some sleep reduction is permissible in the main core sleep. In that case, more naps can be added to the schedule to maintain alertness. Some recovery would be necessary afterwards, as this is not sustainable and builds sleep debt.

During recovery from lost sleep or sickness, it is still necessary to have night sleep placed some time after the start of the dark period to ensure the quality of sleep. For instance, if dark period is set to start at 22:00, place the night sleep at no earlier than 23:00 or so.


  1. GeneralNguyen (2020). "OFFICIAL: The Perpetual Polyphasic Schedule! Final Report & A Comprehensive Guide for a Flexible Napping Lifestyle". Reddit. Retrieved 2020-11-19.