|Nine in 10 teenagers have at least one device in their|
bedrooms. Credit: Getty
The Telegraph, 31 October 2016
Smartphones and tablets in bedrooms disrupt the sleep of children even if they are switched off, a new study has shown.
Researchers at King’s College London and Cardiff University reviewed 11 studies involving more than 125,000 children to find out if technology was impacting sleep.
They found that using smartphones or tablets before bedtime doubled the risk of a disrupted night’s sleep and raised the changes of feeling excessively sleepy the following day by two-fold.
But crucially, sleep was also significantly disturbed by the mere presence of devices – almost to the same level as actually using a gadget – suggesting that they should be removed from bedrooms altogether to improve sleep.
It is thought that the ‘always on’ nature of social media and instant messaging means children are continuously stimulated by devices in their environment, even when they are not using them.
Dr Ben Carter, of King’s College London, said: “Our study provides further proof of the detrimental effect of media devices on both sleep duration and quality.
“Sleep is an often undervalued but important part of children’s development, with a regular lack of sleep causing a variety of health problems.
“With the ever growing popularity of portable media devices and their use in schools as a replacement for textbooks, the problem of poor sleep amongst children is likely to get worse.”
Previous studies have shown that seven in 10 children and nine in 10 teenagers have at least one device in their bedrooms, and most are used near to bedtime.
It is thought that screen-based media devices adversely affect sleep through a variety of ways, including delaying or interrupting sleep time; psychologically stimulating the brain; and affecting sleep cycles, physiology and alertness.
Sleep disturbance in childhood is known to have adverse effects on health, including poor diet, obesity, sedative behaviour, reduced immune function and stunted growth, as well as links with mental health issues.
The new research was published in the journal JAMA Pediatrics.
While you sleep | Your night, broken down
Each night, we go through three phases of sleep: light sleep, deep sleep and Rapid Eye Movement or REM sleep. Each type activates different body processes and neurotransmitters - brain chemicals central to mental functioning. We go through each phase during a 60 - 90 minute cycle, before starting again. During a typical full night’s sleep that cycle might repeat up to six times.
In light sleep, your body temperature drops, and breathing and heart rate become regular.
When you enter phase two, deep sleep, the body releases key hormones. Among these is growth hormone, which contributes to tissue growth and muscle repair. This phase also balances out stress hormones such as adrenaline and cortisol that accumulate during the day. If we have a shortage of deep sleep, our bodies don’t get the time to release and balance all these hormones so the result is waking up with an excess of stress hormones in the body - otherwise known as morning grumpiness.
REM sleep, on the other hand, is when dreams occur and it’s thought to be responsible for daytime performance and the processing of information, emotion and memory processes.