Book: Nurture Shock – Review

Nurtureshock: Why Everything We Thought About Children is Wrong – Po Bronson and Ashley Merryman

This review is only about Chapter 2, since that is about sleep, which is the subject of my current project. The other chapters are equally interesting though! In the chapter ‘The Lost Hour’, the authors describe how children today sleep one hour less than they did 30 years ago and how that impacts their wellbeing.

Like in several scientific papers I read on this subject, it is stated here that a high percentage of high-schoolers feel sleepy during school, their grades drop because of that, and some fall asleep in class. They go as far as to say that the average amount of sleep a child in high school gets, is only 6,5 hours!

The causes for this lack of sleep are the usual suspects: full schedules, early school start times, adolescent circadian clock shifts. Not much time is spend describing possible solutions for this lack of sleep, other than that teenagers who went to bed earlier, got more sleep; their IQ went up and so did their grades. But how to motivate teenagers to go to bed early?

Then an interesting part about adolescents. For reference, I looked up the definition of adolescence in several sources. I was disappointed to find no watertight definition of it, other than some rather vague descriptions without much overlap. The World Health Organisation defines adolescence as the period between 10 and 20 years of age. In the US, adolescent age is often defined as between 13 and 24.

Brown’s Mary Carskadon has demonstrated that during puberty, the circadian system – the biological clock – does a ‘phase shift’ that keeps adolescents up later. In prepubescents and grownups, when it gets dark outside, the brain produces melatonin, which makes us sleepy, But adolescent brains don’t release melatonin for another 90 minutes. So even if teenagers are in bed at 10 p.m. (which they aren’t), they lie awake, staring at the ceiling.

Several experiments with pushing back school start times and letting teens sleep longer, have yielded better results on SAT tests. And interestingly, also typical modern puberescent behaviours like moodiness, depression and binge eating go down with more sleep. Could it be that todays teenagers act out more because of their lack of sleep? The authors of Nurtureshock certainly believe so.

Another side effect of sleep deprivation is an increased chance of becoming obese. Hormone levels change with sleep loss, increasing the feeling of hunger and favouring storage of fat. Furthermore, when you sleep less, you are tired during the day, so you are less likely to have an active lifestyle on top of being hungry. Plus, when you are asleep, you are not eating!

For my research, physical health could be an interesting aspect to define benefits of the proposed nap with. Next to factors like daytime sleepiness, moodiness and cognitive abilities, physical health is important. It would be good to incorporate some measure of that, be it weight, blood pressure or resting heart rate.

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Naps, Cognition, Performance – Review

This paper is one of the proceeds of a symposium held by the authors (“The Effect of Naps on Health and Cognition”, held at the 5th Congress of the World Federation of Sleep Research and Sleep Medicine Societies in Cairns, Australia, September 2007). It describes several research questions and nap-hypotheses, and an agenda for further research on naps is proposed.

Naps, cognition and performance. Gianluca Ficca, John Axelsson, Daniel J. Mollicone, Vincenzo Muto, Michael V. Vitiello. Sleep Medicine Reviews – August 2010 (Vol. 14, Issue 4, Pages 249-258, DOI: 10.1016/j.smrv.2009.09.005)

Practice points:

  • examination of the interrelationships of napping, cognition and performance in four specific contexts
  • the hypothesis that a split-sleep schedule provides more recovery than a single consolidated sleep period of the same total duration is examined. (Correctly timed split-sleep, shown to have positive effects, or at least no negative consequences on neurobehavioral performance, might be used for sleep-wake schedules in work environments that involve restricted nocturnal sleep due to critical task scheduling)
  • the advantages and disadvantages of napping in the work environment are examined. (Napping is an effective important countermeasure to maintain adequate performance levels during extended work shifts, and in operational settings. Napping strategies should be a natural part of programmes having the aim to improve safety and health in the work place. / Short day-time naps are effective on vigilance and cognitive functions for subjects with moderately disturbed sleep and possibly for normal sleepers. Actually, a nap as short as 10 min can improve alertness and performance for about 2.5 h if prior sleep loss exists and for almost 4 h if preceded by normal sleep)
  • benefits of napping for the learning of new material (Naps appear beneficial for memory consolidation of material newly acquired before the nap, either procedural or declarative. More robust effects seem to be given by slightly longer naps, about 60–90 min, possibly due to the build-up of both SWS and REM sleep)
  • whether regular napping among older adults, particularly those in good health, may be beneficial to daytime wakefulness or detrimental to night-time sleep propensity. (The prevalence of spontaneous napping increases with age in adults. This increase is likely the result of increases in nighttime sleep disturbances, phase advance of circadian rhythms, co-morbid medical and psychiatric illnesses and poor sleep habits. / Frequent, unplanned, longer daytime naps in older adults have the potential to negatively impact nighttime sleep quality and may be associated with significant negative health consequences such as increased risk of morbidity, cardiovascular illness, falls and cognitive impairment. / Brief planned naps may be of benefit to the function of healthy older adults, and perhaps even older adults in poorer health)

Research agenda:

  • How and to what extent the neurocognitive effects of naps may change as a function of their circadian placement should be explored in more details.
  • Further studies are needed if we aim to understand the combinatory effects of several countermeasures to maximize alertness at crucial time points: for instance, it would be important to verify how the use of naps and caffeine are best combined in operational shift-work settings.
  • It is still to be understood what sleep features are crucial for the “nap effect” on memory consolidation.
  • Lab studies could seek the effects of naps on specific higher cognitive functions using ad-hoc paradigms and tasks.
  • Research on naps and cognition should include the study of oneiric activity (i.e., dream features) during napping.
  • The cognitive effects of napping at early ages should be explored, because this might be of interest with respect to learning processes and school performance.
  • More elaborate self-report paralleled by objective assessment techniques, such as actigraphy, which allow for a better appreciation of the complexity of napping behavior, should be employed in large, representative samples of older adults which include both nappers and non-nappers.

Especially the second to last point is of interest to me. Would ‘younger children’ also include adolescents though?

Sleep Extension versus Nap or Coffee – Review

HORNE, J., ANDERSON, C. and PLATTEN, C. (2008), Sleep extension versus nap or coffee, within the context of ‘sleep debt’. Journal of Sleep Research, 17: 432–436. doi: 10.1111/j.1365-2869.2008.00680.x

An interesting article comparing three methods of reducing daytime sleepiness against a control group.

The setup was to test one countermeasure each week, in one test day a week, to see the effects of:

  1. usual sleep (control group)
  2. sleep extension (sleeping up to 90 minutes longer at night)
  3. afternoon nap (20 minutes sleep within 30 minute period)
  4. afternoon coffee (2 cups of coffee) Continue reading

Research Question: Effects of Introducing Segmented Sleep in Adolescents

Until now, I have read research, newspaper articles and books on sleep in general, sleeping adolescents, and naps. I have discovered that:

  • adolescents often have a weaker or disturbed biological clock, causing the circadian rhythm to shift or get disordered
  • adolescents are often sleep deprived because of their shifted day-night rhythm, social activities and school work, which negatively influence school achievements
  • contrary to the widely advised solid 8-9 hours sleep per night, possibly our natural sleep pattern is segmented
  • taking a nap has many cognitive and physical advantages

I would like to find out more about the possibilities to fight sleepiness in adolescents with the use of naps, but I have not been able to find many scientific papers on that subject. Perhaps this is a good area to do more research in. In order to study the effects of a nap on teenagers, I need to find out or define:

  • exact definition of a nap: duration, sleep stage
  • test group: age, occupation, social status, health
  • intervention: nap w/o headphones/sleeping mask/hat; environment, posture, caffeine, schedule, duration
  • control group activity
  • standard medical advice for adolescents with sleep deprivation
  • level of sleep deprivation before and after intervention (CSRQ)
  • controlled environment or recommendation + questionnaire

During the project, I will update this post and work towards a good research setup. In the mean time, if you want to read more on sleep: check out this post

The influence of sleep on school performance – Review

Julia F. Dewald, Anne M. Meijer, Frans J. Oort, Gerard A. Kerkhof, Susan M. Bögels The influence of sleep quality, sleep duration and sleepiness on school performance in children and adolescents: A meta-analytic review Sleep Medicine Reviews, Volume 14, Issue 3, June 2010, Pages 179–189 http://dx.doi.org/10.1016/j.smrv.2009.10.004

This paper is a meta-analysis of the relation between sleep and school performance. Meta-analysis is a statistical method combining different study results. It enables the discovery of consistencies in a set of seemingly inconsistent findings.

Sleeping well is important for children and adolescents, since it influences learning and other memory processes.

insufficient or low quality sleep during (early) adolescence impairs the executive function of the prefrontal cortex16 and consequently the decline of learning abilities and school performance. [17] and [*18]

Sleep is crucial for children and adolescents’ learning, memory processes and school performance. [*1],[*2] and [*3]but 45% of children are not getting enough [7] and [8]. On average, adolescents need 9 hours of sleep per night. But as sleep quality is more important than sleep duration, more effective to measure is sleepiness, as this relates directly to enough sleep or not. If a child would sleep 8 hours a night and would not be sleepy during the day, their school performance would not suffer, in contrast to someone who could sleep 9 hours and still be sleepy in school.

Insufficient sleep might be caused by an interaction of intrinsic (e.g., puberty, circadian or homeostatic changes) and extrinsic factors (e.g., early school start times, social pressure, academic workload) leading to later bedtimes while getting up times remain unchanged. Additionally, it is known that approximately 20–50% of children and adolescents report daytime sleepiness. [9] and [10]

We see that daytime sleepiness is highest among children in mid-puberty. This makes me wonder what age group mid-puberty is exactly, so more about that later. The ages of mid-puberty also differ between boys and girls.

mid-pubertal adolescents may need more sleep than younger or older adolescents in order to reach the same level of daytime alertness and neurocognitive functioning. [*2][*16] and [24]

The article ends with a short summary, which is nice to remember where to focus:

Poor sleep quality, insufficient sleep and sleepiness are significantly associated with worse school performance.
We recommend educating children, adolescents, parents and schools about the importance of sleep for school performance. As part of this, education about sleep hygiene can be given in order to improves the sleep of children and adolescent and consequently school performance.
Attention should be drawn to the development of prevention and treatment programs that focus on the sleep of children and adolescents

For more literature on sleep, see this post.

Sleeping in the moonlight… or not

Beautiful poetic post about sleeping. I started to quote some bits, but then I realized all of it is as interesting and important. So here is the whole blog post!

Human Science Explored

Moritz von Schwind, Selene
and Endymion‎, 1831

In 1609, the English writer Thomas Dekker wrote these lines in praise of sleep:

For do but consider what an excellent thing sleep is: it is so inestimable a jewel, that, if a tyrant would give his crown for an hour’s slumber, it cannot be bought … sleep is that golden chain that ties health and our bodies together. Who complains of want, of wounds, of cares, of great men’s oppressions, of captivity, whilst he sleepeth? Beggars in their beds take as much pleasure as kings. Can we therefore surfeit on this delicate ambrosia? Can we drink too much of that, whereof to taste too little tumbles us into a churchyard; and to use it but indifferently throws us into Bedlam? No, no. Look upon Endymion, the Moon’s minion, who slept threescore and fifteen years, and…

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Smart Sleep Literature Links

Following are links to literature I read on the topic of sleep, most recent on top. I will update this list as I go along, hopefully making this post a complete reference at the end of the semester (some articles are protected and can be read on the TU/e network only, sorry). As I go along, I will publish separate posts with reviews for each article and link to those as well. Continue reading