Siesta
Mechanism
Siesta sleep shares a lot of similarities with E1 - when research confirmed the existence of the circadian nadir around noon and early afternoon, both Siesta and E1 become very popular. However, it is most likely that humans naturally sleep in the non-reducing form of these schedules, meaning there is little to no sleep reduction involved. In the case of Siesta, a longer sleep in the nadir region is picked over the short nap of E1. Throughout the course of history, Siesta has been very common in Spain and many other countries around the world. In the context of polyphasic sleeping, Siesta contains 2 core sleeps, because the daytime sleep lasts for 1 full cycle, with much higher restorative power than a short nap. The longer daytime sleep paves the way for a shortened nocturnal sleep, which opens up for more evening time or earlier wake time in the morning. By having more than one core sleep, Siesta is capable of delivering very high sleep quality without compromising long-term health status. Like E1, a bigger portion of total sleep is dedicated to nighttime, where sleep pressure and the need to rest after a long day is often high, while the daytime sleep complements with a bit more sleep to fit into the circadian nadir. Usually, the wake gap from the end of the night core to the daytime core is anywhere between 6-9 hours.
However, unlike most standard scheduling where a core sleep would make use of a multiple of the 90m sleep cycle, the reducing Siesta version (totaling 6.5h each day) utilizes a 5h core (rather than the would-be 4.5h core). This is because the +30m from a 4.5h core can act as a statistically likely REM period, where there is more chance and more room to get extra REM sleep in this 30m duration. Similar to the 6.5h core proposal of E1, it is expected that SWS has been fully covered in the first 3 full cycles of sleep (4.5h) with properly repartitioned sleep and high quality SWS from proper sleep hygiene. On monophasic sleep, the REM cycles in the morning do appear to become longer than 90m, so the 30m help sustain alertness better than a 4.5h core would. This small extension coupled with a daytime core would be equivalent to 4 full cycles from the E1 core.
Adaptation Difficulty
Siesta over the years has reported a great amount of successful adaptations, with the majority coming from the non-reduced version. However, the standard version has overall less success, due to the sleep reduction mechanics that play into the adaptation. It is also likely that when adaptation first begins, waking up from the 5h core (rather than 4.5h) could be difficult with SWS wakes (SWS repartitioning in progress) or REM wakes, due to in the statistically likely REM period. Over time, waking up from the main night core should no longer pose any serious problems, and waking up will become refreshing and invigorating. The daytime core is usually reported to be less challenging to manage, however, for those who are never used to sleeping this long in the daytime hours (or are only accustomed to napping for a short amount of time), it can still be difficult to first deal with the change in sleep habits. Overall, the adaptation progress is mild, if not easier than E1 in some cases. With good time management and a functional alarm setup, most individuals should be able to adapt to the reducing Siesta version.
Alternate Variants
Over the years, a lot of Siesta sleepers have adapted with non-standard variants, including reducing variants. The timing of the core sleeps also report diverse results. Therefore, beginners should look through the differences in the alternate scheduling variations before choosing the desired version to attempt.
- Late core:
Over the years there have been a couple successful attempts with this Siesta variant. The main idea behind this setup is to allow a long wake gap during the day, which suits 9-to-5 mainstream occupations and allows the viability to schedule siesta. A sleeper would have a core at night (albeit much shorter than the usually recommended 7-9h monophasic core), and then a long sleep block to rejuvenate after work. The convenience of this schedule would be a lot of wake time around the evening and up to late night hours. The enhanced mobility of scheduling this variant is also satisfying for many lifestyles.
Despite the advantages, adaptations to this variant are often remarked to be more challenging than to the default version, because shifting the main sleep way out of the SWS peak will often require strong management of food, exercise and dark period to ensure a sufficient amount of SWS. Those with lower SWS requirements will hugely benefit from this setup, as it allows late bedtime and early wakeup time at the same time. The daytime core, being pushed to much later in the afternoon suits the natural tendency of longer sleep as SWS peak (evening hours) draws closer. This core can be pushed all the way to ~7:30 PM and ends at 9 PM in another successful example. It may also be socially intrusive in a way that this long daytime sleep may interfere with other commitments after work.
2. Slightly modified core length:
There has been only one notable case that has adapted to a 5.5h night core. Since there is still a small chance of SWS wakes during adaptation or in the case of high SWS requirements, adapting to this variant is not recommended. The advantage of this core length may benefit high REM requirements, and buffing the total sleep to a safer amount for ~17-18-year-old individuals. The additional 30m may yield a longer period of wakefulness and the daytime sleep can be delayed further.
This Siesta variant would line up with the 90m cycle scheduling rule, however, so far it has reported much less success than the standard version. It is alleged that people with slightly lower monophasic requirements (e.g, 7h) would have a comfortable time adapting to this variant. However, it is also very possible that after adapting to the default Siesta version, the night core can naturally shorten down to 4.5h, but it does not happen very often. With some amount of extra sleep, it is possible to attempt this version if one wants to rake in a bit more extra time during emergency events.
3. Night core extension:
This variant also sees a lot of success, mostly in people with active lifestyles or are still growing mentally and physically. The adaptation difficulty is much milder than the default version, and extending the night core follows the 90m cycle rule (mostly for convenience). This extended version still gives a decent amount of sleep reduction for people whose monophasic need is around 9h each day. The most common form of scheduling this setup is to have a slightly longer core at night and keep the daytime core as it is. However, the night core can still be further extended, which would raise the total sleep higher and become non-reducing Siesta (no sleep reduction from monophasic) if it is preferred. An example would be a 6.5-7h night core, and a 90m daytime sleep for an individual with ~8-9h monophasic baseline.
4. Daytime core extension:
Contrary to the first version of Siesta-extended, this version surprisingly scores some successes thus far, but with a stranger distribution of sleep that looks almost like Segmented sleep. Sleepers who would resort to this variant likely have work hours at night of some sort, and other commitments in the evening. As a result, the night core is often cut short, hence the extension of the daytime core by a full cycle. Ideally in this setup, the dark period would start 1.5-2h before the night core, and resume until ~1.5-2h after the night core to stabilize the circadian rhythm with a solid dark period. Without proper dark period management (e.g, shift work, rotation work hours), it is tremendously difficult to make this variant work, however.
5. Shortened daytime core/Non-reducing variant:
A 60m sleep block is usually discouraged for attempting under most, if not all, polyphasic patterns. However, under non-reducing condition, it can be natural to wake up after 60m rather than a full 90m core. 60m sleeps have been anecdotally researched and tried by a couple of polyphasic sleepers over the years who often naturally fall back to this seemingly "odd" sleep duration. The reason is that the 60m sleep duration provides mostly SWS and the sleeper would likely wake up during the transitional light sleep stage, before the usual REM sleep block would enter. Under non-repartitioned sleep, all sleep cycles follow the regular order, in which NREM1 initiates the cycle, followed by NREM2 (starting to actually fall asleep), SWS (deep sleep, unaware of the surrounding), NREM2 (transition stage) and finally REM sleep. The body at this point has completed the required amount of vital sleep in the day and naturally wakes up, without compressing the core sleeps. However, outside of non-reducing condition, a 60m sleep block should not be scheduled from the start.
Lifestyle Considerations
Siesta sleep has long been considered a golden sleep schedule due to its prevalence and astoundingly well-rounded core sleeps. However, due to the hectic lifestyles today, managing a daytime core is very difficult. This in return decreases the popularity of Siesta and it pales in comparison with its counterpart E1. However, work-from-home or flexible school/work hours can enable the Siesta daytime core to put in work. Over the years a lot of polyphasic sleepers have attempted Siesta, despite its inherently disadvantageous daytime core compared to the daytime nap of E1 and have enjoyed their success. After adaptation, the whole schedule can become flexible by flexing one or both core sleeps with small increments.
However, Siesta (especially extended version) is often known to be the most popular and viable polyphasic pattern for athletes who often perform physically taxing tasks. Roger Federer and Usain Bolt are two of the many athletes who are known to habitually take a long siesta. The secondary core sleep provides more intensive recovery after an intense workout session, effectively granting another opportunity at recovery to meet the increased SWS requirement. It has been researched that after an endurance training session, SWS pressure rises a longer sleep will facilitate SWS. The occurrence of SWS in the long siesta is said to release the growth hormone (GH) regulate glucose levels and glycogen storage as these storages often become depleted under a long and intense exercise session. All in all, the vital functions of the secondary core sleep in assisting the recovery period after exertion is invaluable.
On another note, Siesta sleep is also known to be an adaptation of humans to diseases (including chronic infectious diseases in the study). It seems to make sense that humans sleep for longer periods in a row when severely sick, and with extended core sleeps, it starkly reminds of the non-reducing Siesta version, where both core sleeps last for much longer than usual as a demand for cognitive and physical recovery from sickness. Being a holistically comprehensive schedule, Siesta is one of the best polyphasic schedules that can meet many critical well-being requirements if daily scheduling would give room for it to shine.
