From Polyphasic Sleep Wiki

Flexing is defined as moving sleeps earlier or later from day to day without changing their length.


It was discovered by different community members that it is possible to make polyphasic schedules flexible after adaptation.

During adaptation, when sleep stages aren't repartitioned yet and the sleep structure is not stabilized, in most cases, it is necessary to adhere to ones schedule strictly. Changing sleep times may hinder repartitioning and significantly delay adaptation. However, adapted sleepers often report successful experience with flexing.

It is recommended to stay on an adapted schedule for an extra 3-4 weeks to make sure sleep fully stabilized before trying to flex. It takes two steps to start flexing successfully:

  • Adaptation to a strict schedule
  • Adaptation to flexing

The adaptation to flexible schedules cold turkey has a low success rate and therefore is not recommended.


After the adaptation to a strict base, flexible adaptation can be started. The flex range should be narrow at first, ~5-10 minutes in both directions, gradually increasing step by step.

It is usually easier to flex in these cases:

  • High total sleep time. Such schedules contain more light sleep, thus having less compression. Flexing slightly decreases sleep quality, which is detrimental for the schedules with extreme compression, but is tolerated by the easier schedules. This makes monophasic sleep and other non-reducing schedules inherently more flexible.
  • Naps. Unlike cores, naps contain much less vital sleep, which makes them easier to flex. Among the naps that contain less vital sleep, flexing is even more forgiving. You should avoid flexing cores much since this could possibly destabilize them.

It is difficult to flex in these cases:

  • Low total sleep time. Extreme schedules have to be very rigid to maintain sleep compression. Even a bit of flexing may fully destabilize the schedule and lead to the oversleeping syndrome.
  • Too much at a time. Excessive or random flexing is a receipt for the unstable adaptation and should be avoided. You should gradually test your limits, expanding the flexing range little by little, and stop the expansion as soon as you face signs of sleep destabilization.

Inherently flexible schedules

There is a group of schedules, which are classified as alternating or inherently flexible.


BiphasicX is a flexible biphasic schedule, which potentially includes two blocks of sleep of any given length. This schedule does not require a strict base since it's a non-reducing schedule, which makes it flexible from the very beginning. Though this does not seem to be the case for non-reducing schedules like QC0-extended and other more complex schedules. At least one of the sleep blocks has a natural wake on this schedule, thus making the duration of it alternating from day to day.


The -AMAYL schedules, just as the other flexible schedules, require prior adaptation to a strict base. The differences between these two groups include:

  • Structure. The regular flexible schedules maintain the original structure, and only move sleeps earlier or later from day to day. However, the -AMAYL schedules alternate the number of naps/cores from day to day depending on sleepiness, making it possible to take a new nap/core whenever needed.
  • The range of flexing. Unlike the regular flexible schedules, -AMAYL schedules are many times more flexible. The range is very wide and reaches 24 hours a day on some of them.


After adaptation to the strict base, the adaptation to flexing can be attempted. The range of flexing is gradually increased step by step, followed by switching to the final -AMAYL schedule. The shifting can be done either with just flexing or by flexing and adding a nap, until the alertness levels have risen back up and stabilized. A 10-15 minute shift should take roughly 3 to 4 days to adapt to for each nap shifted, but can take up to a week. After this step is completed the flexing length of the rigid point is increased, one or two naps at a time. After naps are refreshing despite being flexed a small amount, flexing can be increased in larger jumps. The flexing span can be increased by 30-60 minutes each direction, and then up to 2 hours in each direction for each nap. Occasionally add a nap during unusually long wake periods to get used to a variable amount of naps. The nap times should, after this point, be alterable according to the feeling of homeostatic pressure and to make way for duties that require different sleeping times.

Delaying a nap may increase desire to sleep, but once adapted will have no effect on performance, alertness, or general feeling of well-being until it’s delayed excessively – perhaps longer than an hour or two in the morning, or delayed longer than 2-4 hours in the evening. The main advantage of Sevamayl though, is, that you can anticipate in activities that would normally interfere with your sleep time. You can plan an extra nap before, as well as after an event, delaying the default nap.

It is also possible to learn to flex the core sleep. It is going to be harder to do than flexing the naps, but the process is the same. The placement of the core is shifted in small increments from the rigid point until alertness levels have returned to the high standards. This process is then repeated with a larger range. It should be possible to learn to flex the start of the core by as much as 90 minutes with this method, however, it takes longer than adapting to flexed naps. 30 minutes of core flex (e.g. 10:30pm or 11:30pm instead of 11pm) should be comfortable and realistic, and take a week or two to adapt to. It can be done simultaneously while adapting to flexed naps. However, it is unwise to take both to extremes at the same time.

Premature wakes

During the adaptation to polyphasic schedules, some people will start waking up after around 12 to 15 minutes into a nap. When this is the case, the best approach is to attempt to salvage 5 or more minutes of the nap by returning to sleep. Normally these premature wakes last for a few days to a few weeks, but eventually stop occurring. However, on -AMAYL schedules there is no need to return to sleep after a premature wake from naps. If you wake up before your alarm the best strategy is to get up. Though, it should be noted that returning to sleep and sleeping for the full duration of the nap will yield more wakefulness sustaining. What this means is that it is useful to sleep for the full duration of the nap if one’s schedule requires a long gap of wakefulness to be sustained. The premature wakes from the naps is the main reason why they are presented as 15 minutes long on the standard Sevamayl schedule, which is the average nap length. It is also normal for naps taken during the later parts of the day shorten in length, while early naps stay 20 minutes long. Recently, there have been successful adaptations to Sevamayl with occasional extension of a nap after adaptation. One such case, sleeper Gosugenji from the Polyphasic Discord Community has demonstrated that it is possible to occasionally extend a nap duration from 20m to 30m (when a bit more tired than usual to garner more recuperative values from the longer nap) even though his default nap duration is 20m for all naps. This also opens up for even more versatility in nap duration of Sevamayl, when the adaptation phase has been completed. This leads back to the importance of the ability to listen to one’s own body when attempting this schedule.