The influence of the smartphone: Part 6

Written by: Dr Stephanie Thornton | Published:
Image: Adobe Stock

Smartphones are changing the cultural influences on children’s development. In the final part of her six-part series, Dr Stephanie Thornton considers the links between smartphone use and teenagers’ health

Are mobile phones bad for teenager’s health? As discussed in previous articles in this series, using mobile/smartphones can certainly damage concentration and academic performance, can alter socio-emotional strategies, can lead to depression and anxiety – but do they also have a direct impact on physical health?

There are those who argue that mobile phones offer an unprecedented scope for supporting physical health. Smartphones offer a wide range of health apps from sleep and diet monitors to exercise and yoga programs – apps incentivising a wide range of healthy behaviours.

There are also apps designed to help teenagers, their families and doctors monitor and manage health problems such as diabetes more effectively.

And recently, there has been a burst of apps aiming to counter mental health problems such as depression, anxiety, phobias and the like, offered both commercially and by agencies such as the NHS ( and MIND.

Are such health apps effective? Some, such as those monitoring diabetes, are useful (Yan 2017). But for most apps, it is too early to say. Most of these apps are very new, and they are constantly evolving. Research in this area is difficult: it is hard to measure the impact of a moving target, and hard to measure how consistently teenagers actually use a given app, let alone monitor what the effects of using it might be. The result is that there is as yet little or no research on the effectiveness of most health apps (Grist et al, 2017). So, we simply don’t know how useful they will ultimately be.

Although the positive health benefits of smartphones are as yet uncertain, it is already very clear that this technology poses several quite serious risks for physical health. One big worry in this area relates to the impact of teenage phone use on sleep.

The majority of teenagers report that they continue to use their phones after lights out, some continuing all through the night (Vernon et al, 2018). The result is some degree of chronic sleep deprivation in a large percentage of the young.

Typically, the sleep deprived are unaware of the decline in their performance, and so are unaware that losing sleep is causing them harm (Van Dongen et al, 2003). But even small chronic disruptions to sleep can have seriously damaging effects on both physical and mental health. Lack of sleep has well established negative effects on mood, neurological and cognitive function and concentration. It can lead to accidents, sometimes through “micro-sleeps”. The disruption of sleep through night-time use of mobile phones is probably the most widespread damaging effect of these phones, even if there are other factors that have the potential to generate more devastating consequences.

Another heavily researched area has focused on accidents occurring when teenagers are distracted by their phones, for example, not paying proper attention on the roads (Yan, 2017). The risks here are obvious. Older teenagers using a mobile phone when driving, even if hands-free, show markedly slower reaction times – an effect that can be as great as drinking to the alcohol limit. These young drivers are three to four times as likely to have accidents when using a mobile phone, on top of their already greater risk of accidents compared to older drivers (EU Road Safety Observatory, 2015).

Younger teenagers are at risk when using a mobile phone while walking along or crossing roads. Some are certainly involved in accidents, though we do not know how many. Not every such accident is serious enough to be recorded, though most have at least the potential to cause death or life-changing injury.

But probably the biggest worry relates to the fact that using mobile phones exposes the young to radiation. Might this pose risks of cancer? This topic has been addressed in research from the earliest days of mobile phones (Yan, 2017), generating a great deal of controversy.

The problem has been that the explosion in phone use is very recent: a decade ago, only the minority of teenagers had a mobile phone, whereas today virtually all possess one. Radiation at the levels involved here takes time to do its damage and may affect only a minority. So it is only now that we have the numbers to make it possible to form realistic estimates of any effects.

Today, the young are exposed to an electronic environment that is very different from that of the past, as wireless technologies become a core part of our lifestyles. Mobile phones, computers and iPads and the wi-fi signals that serve these devices mean that our young are constantly exposed to low levels of radiation.

A major review of research into the effects of this exposure (Sage & Burgio, 2018) yields a number of worrying conclusions.
Research has now demonstrated that chronic exposure, even to the very low levels of the kind of radiation associated with mobile phones and tablets, wi-fi laptops and so forth, can have biological effects.

It is worth emphasising that these effects occur from exposures to levels of radiation well below those permitted by current public health recommendations. This exposure may cause epigenetic changes in gene expression.

Sage and Burgio reviewed a range of research showing that exposure to wi-fi technologies can disrupt normal neurological, immune and metabolic processes, leading to problems in concentration and attention, disruption to learning and other mental functions.

There is evidence that such exposure can cause symptoms similar to those of ADHD or autism. It can also cause a variety of chronic physical health problems, including some serious ones. For example, there is now clear evidence, both from animal studies and from human epidemiology, that the radiation associated with mobile phones increases the risk of brain cancer. And in fact, wi-fi exposure has been listed by WHO as a health hazard, specifically as a possible carcinogen, since 2011. The risks are greatest in the young – in children and teenagers up to age 20.

Mobile phones offer a wide range of very obvious benefits and they are here to stay, despite the risks that are now becoming clear.

What can we do, to reduce those risks? Expert opinion suggests that we should be more direct in talking to the young about the risks associated with mobile phone use:

  • It may seem obvious that driving/crossing a road while focused on your phone is dangerous, but sometimes stating the obvious to teenagers can make a real difference.
  • Likewise, we assume that teenagers understand the importance of sleep and the damage caused by sleep deprivation. But in reality, most probably either don’t understand this, or don’t take it seriously. Expert advice recommends discussing this issue with the young, and a ban on phones in the bedroom overnight.
  • As to the hazards posed by radiation from wi-fi devices: this technology is not going away. Teenagers should be made aware of the risks, and of the fact that they can reduce the risk by reducing the amount of time they spend using their phones. In addition, there are steps schools can take to reduce exposure: banning phones from schools would have such an effect, for example. And perhaps we should reduce the exposure to radiation by returning to using wired, rather than wi-fi-connected computers in the classroom.
  • Dr Stephanie Thornton is a chartered psychologist and former lecturer in psychology and child development. To read Dr Thornton’s previous articles in SecEd, including in this series, go to


  • Cell phone use while driving, EU Road Safety Observatory, 2015.
  • Mental health mobile apps for preadolescents and adolescents: a systematic review, Grist, Porter & Stallard, 2017, Journal of Medical Internet Research:
  • Electromagnetic fields, pulsed radiofrequency radiation and epigenetics: how wireless technologies may affect child development, Sage & Burgio, 2018, Child Development.
  • The cumulative cost of additional wakefulness: dose response effects from chronic sleep restriction and total sleep deprivation, Van Dongen, Maislin, Mullington & Dinges, March 2003, Sleep, Vol 26, Iss 2.
  • Mobile phones in the bedroom: Trajectories of sleep habits and subsequent adolescent psychosocial development, Vernon, Modecki & Barber (2018) Child Development.
  • Child and Adolescent Use of Mobile Phones: An unparalleled complex developmental phenomenon, Yan, Child Development, May 2017:


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