The Chronic Sleep Reduction Questionnaire – Review

DEWALD, J. F., SHORT, M. A., GRADISAR, M., OORT, F. J. and MEIJER, A. M. (2012), The Chronic Sleep Reduction Questionnaire (CSRQ): a cross-cultural comparison and validation in Dutch and Australian adolescents. Journal of Sleep Research, 21: 584–594. doi: 10.1111/j.1365-2869.2012.00999.x

Through the use of the Chronic Sleep Reduction Questionnaire (CSRQ), the researchers try to assess symptoms of chronic sleep reduction in adolescents. While this paper is mostly about validating this approach, the information is very useful to see how such experiments are set up, and their conclusions. Also the questionnaire itself can be a useful tool in further research. Continue reading


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

Book: Functional Anatomy of the Sleep-Wakefulness Cycle – Review

Functional Anatomy of the Sleep-Wakefulness Cycle

This book is mainly about the specific nerves, hormones and other body parts responsible for sleep. Of course I should have known from the title, which has ‘anatomy’ in it, but this particular book was not too helpful for me. In a big part due to the fact I could not really read about the various experiments without gagging. But I concentrated and read through at least one particularly creative experiment.

The Sleep-Wakefulness-Cycle (SWC) simplified, exists of three stages: wake, non-REM sleep, REM sleep. Rapid Eye Movement (REM) sleep, is when you dream. Apparently, the cycle becomes longer in time, later in the night, which could explain why most people remember more complex dreams in the morning compared with when they wake up in the middle of the night. Also REM sleep is diminished in older people.

An experiment is described to see whether input on the body, influences the SWC. Normally, darkness causes certain hormones to be released which is why people and many animals sleep at night and are awake at day. The brain gives the command to release the hormones. But does the animal ‘know’ that its night, through his body or brain?

The conclusion was, that influences on the spinal cord nerves, must be responsible for the circadian rhythm. In other words, our brain does not dictate when we sleep, our body does!

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

Rethinking Sleep – Review

Brendan Monroe

From the New York Times: Rethinking sleep by David K. Randall

Mr. Randall states that we only started believing in 8-solid-hours-sleep in Western society, and only after the industrial revolution. Perhaps midday naps were unpopular to factory owners? There are other unhealthy sleeping habits connected to the industrialized world: think of shift work and night jobs.

But even today, in many societies naps are a way of life. In Spain, although in decline, people take a siesta after lunch, the main meal of the day. In China and other Asian countries, taking a powernap at your desk makes you seem motivated and effective, not lazy.

Further in the article, texts from historical records like Shakespeare are cited as proof that daytime sleeping was once common.

A character in the “Canterbury Tales,” for instance, decides to go back to bed after her “firste sleep.” A doctor in England wrote that the time between the “first sleep” and the “second sleep” was the best time for study and reflection. Continue reading

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

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.

Chronic Sleep Reduction and School Achievement – Review

MEIJER, A. M. (2008), Chronic sleep reduction, functioning at school and school achievement in preadolescents. Journal of Sleep Research, 17: 395–405. doi: 10.1111/j.1365-2869.2008.00677.x

An interesting study on the effects of chronic sleep reduction on the school results of 7th and 8th grade school children. The conclusion is that chronic sleep reduction affects school achievements negatively, directly and indirectly. How does this work?

Chronic sleep reduction can occur by sleeping too shortly or having poor quality of sleep (interrupted), over a longer period. Consequences of chronic sleep reduction can include: