Age Considerations

Introduction

At younger age, humans generally require more sleep. This particularly affects those who are underage (under 18 years old) and have not fully matured yet. This is because they are still growing both mentally and physically1.

  • Extra SWS time is necessary to support bodily growth, learning, and memory retention.
  • The total amount of light sleep is lower and there is a higher percentage of REM and SWS in daily sleep totals2.
  • Because light sleep could play a part in development3,4,getting as much sleep as possible is also likely necessary. Consequently, the total amount of viable daily sleep reduction is very small.
  • Underage people should also absolutely avoid any polyphasic sleep schedules with significant sleep reduction

General Guidelines

The polyphasic sleep community uses the following lifestyle consideration values as a baseline:

<16 years

A sample non-reducing Siesta

Sleeping the recommended amounts is highly encouraged. Both the brain and the body are in full development and highly sensitive. The negative side effects of polyphasic sleep are by large unknown; thus, there is a good reason to take precautions similar to nicotine or alcohol.

Both of these are equally subpar or even detrimental during development. With artificial lighting causing the advancement of circadian rhythm and an early start of the school day, segmenting their sleep may be helpful in achieving refreshing sleep duration that would otherwise not be possible. At best, you can attempt non-reducing biphasic schedules for optimal health benefits. 

16-18 years

At least 6h of sleep, and potentially more if possible. The body and brain are both still developing, but at a lesser extent than previously. However, this period is one of the most important ones during life. In modern society, high school performance has great impact on future outlooks.

It may be worth taking this into account as improper experimentation with your sleep can affect the day-to-day performance. The best interest would still be no sleep reduction if you are concerned about your own health. 

18-21 years

At least 5h of sleep. The body has developed to some extent; however, the brain is still developing. In addition, this development process may also conclude later in some other individuals. 

Similar to the previous age milestones, you may totally not reduce sleep duration on your polyphasic schedule or only minimally reduce duration. This is if you are still skeptical about sleep reduction at a young and developing age. 

21-25 years

Over 4h; the brain can still be in the final stages of development. Dropping below 4h is generally advised against, even after 25. Furthermore, younger adults have generally less structured lifestyles. You should really consider this factor if it applies to you. More details are in the following sections. 

Minimum Sleep Requirements

Minimum polyphasic requirements are estimates based on community experience and do not constitute medical advice. This is because sleep need varies among people and circumstances.

Age Minimum Hours of Daily Sleep
<16 7.5+ polyphasic/ 9+ mono8/no sleep reduction
<18 6.3+ polyphasic/ 
8-9+ mono/
avoid reducing total sleep
<21 5 – 6+ poly
>21 4 – 5+ poly

 

If a desired schedule pattern fits your schedule but is below your threshold, you may add at least 90 minutes to the core to secure your well-being. In the case of Siesta-extended, use a 6 hour core with your 90-minute siesta.

More Data on Adolescent Sleep

In addition to the general guidelines above, it is important to consider that some people, especially males, can have growth spurts as late as at 19 years old5. During this period, SWS need increases. It is debatable whether people who are 17 can actually drop down to 5h of sleep, but it is probably best to avoid doing so. 

Timeline of Brain Development

The rational part of the brain develops until the age of about 25 years old6 (possibly longer7,8). This means the safest course of action is to avoid reducing the total amount of sleep at least until that age. This also means no experimenting with extreme schedules until later.

  • At 11 years old: The amygdala and hippocampus should complete their maturation process.
  1. Specifically, the amygdala is responsible for storing memories of events and controlling emotions. For example, sadness, anger and aggression. 
  2. On another spectrum, the hippocampus is accountable for formulating new memories. It is also associated with learning and emotions.
  • 12 years old: Brain synapses have achieved density similar to those in adults. Additionally, the grey matter (brain neurons) in the frontal lobe and parental lobe reaches its peak. Thus, its peak may explain that it has fully matured at this point.
  • 13 years old: Brain areas involved in special orientation and languages have matured. 
  • 16 years old: Human corpus callosum, the nerve fiber bundle beneath the cerebral cortex, has finished its thickening process. It serves to enhance the ability to process information. At this age, the gray matter in the temporal lobe also peaks; therefore, this notion explains why the community advises against any sleep reduction amounts before this age. 
  • 20 years old: Most white matter tracts reach their peak. At this moment, the large proportion of your brain has matured. However, there are still incomplete brain regions.
  1. These white matter tracts consist of myelinated axons.
  2. Most notably, they are responsible for learning, regulating brain functions and communicating between brain regions.
  • 25 years old: The prefrontal cortex fully matures. This is especially critical because the prefrontal cortex is behind rational, not emotionally-driven decisions. Furthermore, the brain has developed to the fullest by this age. 

Scientific Sleep Recommendation for Teenagers

A growing body of scientific research support these recommendations:

  • Adolescents require > 9h of sleep at night.  Some even require additional daytime sleep.
  • In controlled conditions with 10 hours allocated for sleep, 10-17-year-olds needed 9.25h of sleep per night regardless of age. In addition, at mid-puberty, there was an increased tendency for daytime sleep even with sufficient night-time sleep9.
  • Delayed sleep-wake behavior is present predominantly in Asian cultures. As a result, this causes decrease in total sleep during adolescence (for review, see10). This is regardless of the amount of sleep needed to achieve optimal day-to-day performance.
  • Many studies have demonstrated that on average they obtain between 7.5 and 8.5 h per night; about a quarter of adolescents obtaining < 6.5h per night and only 15% obtaining 8.5h or more9,11.

We strongly recommend only attempting schedules with a safe amount of sleep for your age. Ironically, many younger people do not feel sleep deprived when reducing sleep below safe levels. Long-term consequences to development are still a risk regardless of how you feel4–7.

Main author: Crimson & GeneralNguyen

Page last updated: 1 February 2021

Reference

  1. How Much Sleep Do Babies and Kids Need? National Sleep Foundation. https://www.sleepfoundation.org/excessivesleepiness/content/how-much-sleep-do-babies-and-kids-need. Published 2018. Accessed November 4, 2018.
  2. Nicolas A, Petit D, Rompré S, Montplaisir J. Sleep spindle characteristics in healthy subjects of different age groups. C. 2001;112(3):521-527. doi:10.1016/s1388-2457(00)00556-3
  3. PEIRANO PD, ALGARÍN CR. Sleep in brain development. B. 2007;40(4). doi:10.4067/s0716-97602007000500008
  4. Chatburn A, Coussens S, Lushington K, Kennedy D, Baumert M, Kohler M. Sleep Spindle Activity and Cognitive Performance in Healthy Children. Sleep. 2013;36(2):237-243. doi:10.5665/sleep.2380
  5. Soliman A, De S, Elalaily R, Bedair S. Advances in pubertal growth and factors influencing it: Can we increase pubertal growth? Indian J Endocrinol Metab. 2014;18(Suppl 1):S53-S62. [PubMed]
  6. Sather R, Shelat A. Understanding the Teen Brain. University of Rochester Medical Center . https://www.urmc.rochester.edu/encyclopedia/content.aspx?ContentTypeID=1&ContentID=3051. Published 2018. Accessed November 4, 2018.
  7. Trafton A. The rise and fall of cognitive skills. MIT News. https://news.mit.edu/2015/brain-peaks-at-different-ages-0306. Published March 6, 2015. Accessed November 4, 2018.
  8. Hartshorne JK, Germine LT. When Does Cognitive Functioning Peak? The Asynchronous Rise and Fall of Different Cognitive Abilities Across the Life Span. P. 2015;26(4):433-443. doi:10.1177/0956797614567339
  9. Moore M, Meltzer LJ. The sleepy adolescent: causes and consequences of sleepiness in teens. P. 2008;9(2):114-121. doi:10.1016/j.prrv.2008.01.001
  10. Gradisar M, Gardner G, Dohnt H. Recent worldwide sleep patterns and problems during adolescence: A review and meta-analysis of age, region, and sleep. S. 2011;12(2):110-118. doi:10.1016/j.sleep.2010.11.008
  11. Iglowstein I, Jenni O, Molinari L, Largo R. Sleep duration from infancy to adolescence: reference values and generational trends. Pediatrics. 2003;111(2):302-307. [PubMed]