Tuesday November 29 2016

Children need more sleep than adults

“New brain scans reveal sleep deprivation damages children’s brains more than previously thought,” the Mail Online reports.

Researchers measured the brain activity of children whose sleep had been restricted by four hours and found some potentially worrying signs.

The study included 13 children aged between five and 12 and compared the effects of a normal night’s sleep (9pm bedtime) with a restricted night’s sleep (2am bedtime), both with the same wake up time.

Previous studies in adults have shown that sleep restriction increases deep sleep waves – patterns of brain activity associated with the deepest sleep – in the front region of the brain.

The researchers found similar effects in children, but this time at the back and side regions of the brain involved in planned movements, spatial reasoning, and attention.

The researchers were concerned this could impact on the development of the brain. Neural structures inside the brain change and adapt to the stimulus the brain receives; a concept known as plasticity. The worry is that the deep sleep waves could disrupt or slow down normal plasticity development.

They also found that sleep deprivation was linked with some structural changes to the myelin sheath – the fatty coating on nerve fibres going towards the back of the brain. However, it’s quite a big step to say this results in disruption to brain development.

This study was tiny, and observed short term effects. We have no idea whether similar sleep deprivation would have any long-term effect on a child.

Where did the story come from?

The study was carried out by researchers from a number of institutions including the University of Colorado and University Hospital Zurich.

Funding for the research was provided by the Swiss National Science Foundation, the Clinical Research Priority Program Sleep and Health of the University of Zurich, the Jacob’s Foundation and the National Institutes of Health.

The study was published in the peer-reviewed medical journal Frontiers in Human Neuroscience on an open-access basis so it is free to read online.

The Mail Online’s reporting of the study was generally accurate but some of the language used in the reporting was over the top. While the results of the study certainly deserve consideration, claims that they amount to “staggering damage” are unproven and exaggerated.

What kind of research was this?

This is a cross sectional study which aimed to assess whether sleep deprivation in school age children could have an effect on brain activity and development.

The researchers explain how previous research in adults has shown that the brain responds to sleep deprivation by increased depth of sleep (non-REM sleep).

This has been demonstrated by increased slow-wave activity (SWA) when monitoring the person’s brain while they slept, using an electroencephalogram (EEG). An EEG uses a series of sensors placed around the scalp to monitor the electrical activity of the brain. SWA shows up as a distinct wave-like pattern.

When adults are sleep deprived, this SWA response is usually seen in the front of the brain. The researchers chose to study children as it is not known how their brain responds to acute sleep restriction, and whether any effects seen could be related to brain development.

This kind of study is good for identifying patterns but the very small sample size may make these results unreliable. It is also not able to predict whether these changes may affect longer term outcomes.

What did the research involve?

The researchers included 13 healthy children with no sleep problems aged between five and 12 years. The children were given a sleep programme to follow – either habitual sleep, going to bed around 9pm, or a restricted sleep of 50% of their normal bedtime where they went to bed at about 2am. Both groups had the same morning wake time of 7am.

The restricted sleep group were kept awake by interacting with the research team playing games or reading. The programme was verified by actigraphy, a non-invasive method of monitoring activity that use devices similar to commercial fitness tracker wrist bands, and sleep diaries.

While they were asleep, the children’s brain wave patterns were monitored by EEG, where electrodes are attached to the scalp and send signals to a computer to record the results.

Three different time windows were analysed in both sleep settings:

• The first hour of sleep – to see the effect of restricted sleep when under the greatest level of sleep deprivation.
• The final hour of sleep – to compare the effect of restricted sleep just before waking up.
• The last common hour of sleep – comparing brain activity after a common duration of sleep in both scenarios (this would be the 6-7am sleep window if going to sleep at 2am, compared to the 1-2am sleep window if going to sleep at 9pm).

Magnetic resonance imaging (MRI) was used in all children to measure the level of myelin present; this is a fatty coating around the nerve fibres in the brain and which transmits nerve signals. The researchers looked at this as a possible marker for the effects on brain development.

What were the basic results?

In general the researchers found that when sleep was restricted, the children, like adults, had increased depth of sleep, or non-REM sleep, as indicated by increased slow-wave activity (SWA). However, the brain location was different to adults.

Rather than the front regions of the brain, SWA was towards the side and back regions of the brain (parieto-occipital region).

This area of the brain has many functions including processing visual signals (occipital lobe) and sensory information (parietal lobe), so affecting planned movements, spatial reasoning, and attention.

It appears that for children this region may be more susceptible, and possibly vulnerable, to a lack of sleep.

Sleep restriction also seemed to be linked with the amount of water in the myelin coating a developing optic nerve fibre towards the back of the brain on both sides. The potential implication(s) of this are unclear.

How did the researchers interpret the results?

The researchers conclude that the short wave activity response to acute sleep restriction in children shows an effect on the ongoing refinement of the nerve fibres with observable changes to the structure of the myelin sheath.

They suggest “future studies are needed to investigate the functional consequences of inadequate sleep during different stages of development and to identify the key factors involved in the generation of the posterior homeostatic response in school-age children” – roughly translated to how balance is achieved in the back portions of the brain.

Conclusion

This cross sectional study aimed to see whether sleep restriction in children could affect brain activity in a similar way to adults, and whether this may have an effect on brain development.

They found that sleep deprivation does lead to deeper sleep patterns in the side and back regions of the brain, and this also seemed to be linked with an effect on the myelin coating certain nerve fibres.

This potentially indicates that sleep deprivation may affect the developing brain of school age children – but this is quite a big leap.

The findings might seem worrying to parents and children but it’s important to note the number of limitations to this study.

Firstly, this is a very small study including only 13 healthy children without sleeping problems. The same findings in these children may not be repeated in another sample of children.

They also can’t tell us whether similar or different effects would be observed in children who have sleep difficulties. For example, children who regularly have reduced or disrupted sleep for whatever reason may have developed adaptive mechanisms.

As the study did not take measurements over a very long period of time we also don’t know whether the observed changes are long lasting. This would need to be assessed in further research.

Finally, we have no idea whether the effects observed would actually have an impact on the child’s learning, development or day-to-day function.

Trouble sleeping can be a problem for children and adults, however there are things you can do to try and get a better night’s sleep.

A minimum of 9 to 11 hours sleep a night is recommended for children aged 5 to 12.

Encouraging children to exercise for at least 60 minutes a day, cutting out caffeinated drinks such as cola during the evening, and not overeating before bedtime can help children have good quality sleep.

Read more about sleep advice in children.