Appetitive Napping

Introduction

This napping method is defined as napping even when not tired, but for psychological benefits such as restorative effects from napping1. It is also done without any relation to sleep needs2, but rather from napping as a routine. Because of the nature of this napping behavior, it is consensually agreed that short appetitive naps (~20 minutes) contain mostly NREM12  because of low sleep pressure, and is equivalent to a shuteye (under non-reducing biphasic conditions or normal monophasic sleepers casually taking a nap). Under these conditions, the appetitive nap is similar to a form of meditation to relax the mind without actual sleep. However, with sufficient napping experience, appetitive napping can be used as a method to sustain polyphasic schedules after the adaptation phase and a way to retain napping skills between adaptation attempts. Yet, certain conditions mentioned in this blog post need to be met to effectively use appetitive naps. 

Appetitive naps in polyphasic sleeping

Appetitive napping in general provides more benefits for adapted/experienced polyphasic sleepers than for non-nappers; after the adaptation phase is completed, these polyphasic sleepers can manage to schedule naps outside their base schedule (with a certain extent of flexibility) and still fall asleep in the new naps a lot more quickly than non-nappers (e.g, flexible schedules like SEVAMAYL). It is reasonable to say that adapted/experienced polyphasic sleepers know how to take full advantage of napping and show better napping skills than beginner nappers. This suggests that appetitive naps have the potential to provide deeper sleep stages if the timing matches with alertness dips, especially under sleep deprivation and high homeostatic pressure. However, whether being able to fall asleep at random hours outside the rigid base of the adapted polyphasic schedule is considered healthy or perpetually tired is yet to be concluded, even though napping spontaneously outside the base schedule can be difficult at first (the first step of learning to flex naps). This has a high chance to make the naps inefficient (NREM1 naps) until the napper has adapted to flexing naps. 

Despite its nature, results indicated some benefits from appetitive napping behavior. Subjective assessment from each experimenter was mostly positive, feeling less tired after each nap2. Habitual appetitive nappers also showed consistent sleep onset latency at night and during the daytime naps. Based on the EEG results2, it is interesting to observe that appetitive nappers do fall asleep in their naps over time if the nap is long enough to contain SWS (> 30 minutes); appetitive nappers took 22 minutes to actually fall asleep, but managed to get 16 minutes of NREM2 and 16 minutes of SWS in the 60-minute naps. Once again, this result seems to hint that appetitive naps have longer sleep onset latency than scheduled naps on rigid polyphasic schedules and require longer sleep duration to contain deeper sleep stages, thanks to their spontaneous nature.

In another study, it was demonstrated that appetitive nappers were not only able to fall asleep almost anywhere and at different times during the day but also able to fall asleep at night without reducing total sleep, and night sleep is not disrupted1. This result supports the previous hypothesis about how at least some experienced polyphasic sleepers appetitively nap. Most importantly, it is also worth noting that appetitive nappers consistently had lower total sleep duration at night than non-nappers on the days they napped1. Quite possibly, nocturnal sleep duration in appetitive nappers might automatically slightly reduce over time compared to their monophasic sleep need, but remains consistent with their monophasic baseline when the appetitive nap duration is accounted for. This observation is based on only non-reducing biphasic sleep patterns from the above study. It is important to note that adding a daily nap into a monophasic sleep schedule (to become biphasic sleep) is likely to train sleepers to learn to fall asleep in the nap. This opens up the possibility that napping is a skill that can be learned and sleepers will eventually become skilled nappers. 

When and when not to appetitively nap on polyphasic schedules

When it is beneficial:

The following scenarios go well with appetitive napping:

  1. Flexible, non-reducing biphasic and random schedules. New polyphasic sleepers can appetitively nap on these schedules to learn to nap more effectively. Appetitive naps have been proven to work with this specific type of biphasic sleep or flexible, random sleep patterns that allow napping whenever tired. 
  2. During emergency situations (e.g, apocalyptic, do-or-die events) where extreme sleep reduction is required, appetitive naps are often used to sustain alertness as sleepers do not have the luxury to have long, uninterrupted core sleeps. Napping even when not tired can be better than getting no sleep at all, even if the naps are too short to contain deeper sleep stages. 
  3. People who have the natural ability to sleep during daytime yet showing any signs of daytime sleepiness or being affected by notable sleep pressure3. These individuals have the ability to fall asleep rapidly and can turn appetitive naps into actual naps to adapt to polyphasic sleeping. This ability also helps these individuals get some rest during emergency situations or when they do not follow any specific sleep patterns. 

When it is not a good idea:

  1. During the adaptation phase. Napping spontaneously outside the scheduled sleep times is considered an “oversleep” even if the sleeper is not tired. Thus, it is important to stick to the scheduled rigid sleep times as consistently as possible. 
  2. Nap time is too close to the nocturnal core sleep. Even in the case of new polyphasic sleepers who miss the daytime nap and want to nap later on, this is not recommended. Naps within 2-3h prior to the nocturnal sleep can clash with the Forbidden Zone of sleep, making the nap ineffective and not restful (NREM1 nap). If the sleeper falls asleep in this late nap, it can interfere with the core sleep via 2 ways: delaying the desired nocturnal sleep time or increasing sleep onset latency if the sleeper attempts to sleep at the regular hour. 

Conclusion

Conclusively, appetitive napping behavior is a harmless yet useful practice to kick start polyphasic sleeping, to facilitate falling asleep in naps and a smooth transition into schedules with more than one nap. However, it seems to require correct timing in the day to actually make use of the appetitive naps – without sleep deprivation and homeostatic pressure, it is likely that the appetitive naps do not sustain alertness for as long as naps that contain deeper sleep stages (NREM2, SWS and REM). Naps where sleepers can get some actual sleep is still preferred for more restorative values from deeper sleep stages. Experienced polyphasic sleepers have better napping aptitude to make appetitive naps more efficient than inconsistent nappers or non-nappers. 

 

Main author: GeneralNguyen
Page last updated: 30 April 2020

Reference

  1. Stampi, Claudio. Why We Nap : Evolution, Chronobiology, and Functions of Polyphasic and Ultrashort Sleep. Birkhauser, 2014.
  2. Evans, F. J., et al. “Appetitive and Replacement Naps: EEG and Behavior.” Science (New York, N.Y.);197(4304):687–689. doi: 10.1126/science.17922. [PMC]
  3. Harrison, Y., & Horne, J. A. “High sleepability without sleepiness”. The ability to fall asleep rapidly without other signs of sleepiness. Neurophysiologie Clinique/Clinical Neurophysiology. 1996;26(1):15–20. doi:10.1016/0987-7053(96)81530-9 [PMC]

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