Ten guidelines for a healthy life: Korean Medical Association statement (2017).
December 15, 2017 148 p (in English)

doi: https://doi.org/10.26604/979-11-5590-078-9-93510-10

Avoiding Excessive Exposure to Mobile Devices

Avoiding Excessive Exposure to Mobile Devices

Smart use of smart devices


◆ Background

Excessive use of smart devices impedes concentration and causes negligent accidents. Exposure to blue light before sleep creates a vicious cycle of fatigue, because it disrupts the circadian rhythm, reducing the quality of sleep and increasing tiredness the next day. This is especially problematic for preschoolers and children.

◆ Purpose

To help people learn how to use smart devices properly, which would help prevent depression and anxiety, reduced quality of sleep, decreased work efficiency, and distress in interpersonal relationship caused by the excessive use of smart devices.

◆ Contents

1. Avoid smartphones while eating

Increased smartphone use means decreased physical activities, and continuous exposure to blue light influences overeating. Let’s cultivate a healthy eating habit: no smartphones while eating.

2. Avoid smartphones before sleeping

Excessive light from smartphone screens late at night disrupts the normal circadian rhythm and causes insomnia. Therefore, smartphones should be avoided for 2 hours before going to bed; you should perceive your bed not as a place to use a smartphone, but as a place to sleep.

3. Keep smartphones away from babies

Interaction with the real world is essential for the development and differentiation of the brain in infants and young children. Therefore, when infants and toddlers under age 2 use smartphones, their cognitive development can be negatively affected, as well as their physical development, since smartphone use at an early age causes turtleneck syndrome and scoliosis.

◆ Expected impact

By providing information about the proper place, time, and age for using smartphones, this chapter helps people ensure that they receive adequate mental rest and prevent insomnia. In particular, the points made in this chapter will help ensure the normal cognitive and physical development of infants and young children.

Keywords: Smart device, Addiction, Obesity, Insomnia, Brain development

Best practices to follow

1. Avoid smartphones while eating

2. Avoid smartphones before sleeping

3. Keep smartphones away from babies

Fact Sheet ➊

Avoid smartphones while eating

1.1 Do not use a smartphone while eating

When people choose what to eat while using smart devices, there is a strong possibility that they will choose easy and convenient processed food (Fig. 10.1). Studies suggest that people tend to eat more after-meal snacks when they play computer games during meals. According to a report from the Harvard School of Public Health, adolescents who use smart devices, such as a smartphone or tablet, for more than 5 hours a day are twice as likely to consume high-sugar beverages, twice as likely not to engage in any physical activities, and 79% more likely to experience sleep deprivation. As a result, their likelihood of being obese is 43% higher than adolescents who do not use smart devices [1]. Longer and more frequent use of media devices reduces their physical activity, and it makes them more likely to be exposed to food commercials, which in turn makes them more likely to consume snacks or soft drinks at home. More use of media devices means less use of their body; media consumption and computer games have been reported to decrease children’s outdoor activities, playing an important role in increasing the incidence of child obesity [2]. Moreover, these factors make people prone to consume more food than usual even when they are not hungry; according to a previous study, people ate more food when they were absorbed in computer games [3]. Another study reported a correlation between overeating and extended exposure to blue-enriched light from LED screens. Compared to dim light, continuous exposure to blueenriched light has a greater influence on insulin metabolism and blood sugar levels in the morning and the evening [4]. These factors can cause weight gain; therefore, it is recommended to cultivate the habit of not using your smartphone during meals.

Figure 10.1

Smartphone use during meals.

When people choose what to eat while using smart devices, there is a strong possibility that they will choose easy and convenient processed food


1.2 Set a purpose and particular times for smartphone use

Smartphone use while walking causes accidents all around the world, which gave rise to the new coinage, ‘smombie’ (smartphone zombie). Moreover, smartphone use while driving is one of the main causes of traffic accidents (Fig. 10.2). More and more pedestrians are getting injured because they were either looking at their smartphones or wearing earphones, making them oblivious to the passing cars nearby [5].

Figure 10.2

Examples of warnings against smartphone use while walking.

Using a smartphone while walking or driving increases the risk of accidents.


Smart devices make it possible to engage in multitasking, which means processing multiple sources of information simultaneously. Although multitasking is advantageous in that it allows us to take care of many tasks within a short period of time, it has the disadvantage of limiting our thought process to a superficial level. Some studies have reported that people who engage in multitasking excessively might experience decreases in their concentration and memory, and their filtering ability (ability to filter out unimportant pieces of information) might seriously decline [6,7].

Our brain also needs rest. Normally, beta brainwaves prevail when we are in the waking state of consciousness. However, an examination of online gamers showed that their beta waves decreased when they took a break, meaning that their brains were out of balance. In other words, a state of hypoarousal, which includes signs of being ‘spaced out,’ was detected [8]. To prevent such negative effects, setting a purpose and particular times (e.g., texting, online searching, social networking, business-related tasks, etc.) for each smart device (e.g., tablet, cellphone, or laptop) is recommended. According to a recent study in Korea, proper management and treatment of internet/smartphone addiction improved patients’ inhibitory control ability by 2.5 times, and it ameliorated their psychological quality of life by 13.6% [9].


Fact Sheet ➋

Avoid smartphones before sleeping

2.1 No smartphone use within 2 hours before bedtime

Late night is the time for rest; be wary of late-night exposure to excessive light from screens, especially blue light, as it causes disruption of the circadian rhythm, which in turn affects one’s health negatively [10].

Insufficient sleep due to the overuse of smartphones and electronic devices can negatively impact the growth and development of children and adolescents. If one uses smart devices after 10:00 PM, the secretion of melatonin (a hormone signaling the brain to fall asleep) is disrupted and the sleep cycle is disturbed, making it difficult to fall asleep. Studies have reported that 2 or more hours of exposure to blue light from tablets suppressed melatonin secretion, and that the arousal effect increased in proportion to the intensity and length of the light exposure [11]. Then, bodily functions such as the secretion of growth hormones are also more likely to malfunction, and the decrease in the quality of sleep inevitably has an adverse effect on one’s social activities and school performance, as one feels drowsy during the day [12]. Therefore, it is best to keep your distance from smart devices for at least 2 hours prior to bedtime. If you must use them, you should download an app that automatically reduces the blue light at night. Taking a hot bath will be helpful if you have difficulty falling asleep, and you need to use your bed not as a place to use smart devices, but as a place to sleep.

2.2 Don’t use a smartphone while lying down

Using a smartphone for a long time can cause pain in one’s neck and arms, which is a chronic disease of modern people [13,14].

Computer use is related to musculoskeletal disorders. The longer you use a computer, the more likely you are to experience symptoms related to musculoskeletal disorders, such as carpal tunnel syndrome and tendinitis of the wrist and shoulder [15]. It is also certain that other factors—stress, psychological factors, long-time sustained postures, absorption in a task—can cause such musculoskeletal problems. The causal nature of the relationship between smartphone use and musculoskeletal disorders has not been clearly proven; however, it is still important to maintain a good posture when using these devices for a long time. It is also vital to get enough rest and to engage in occasional stretching.

Fact Sheet ➌

Keep smartphones away from babies

3.1 If possible, keep infants and toddlers age 2 and younger away from all smart media

For the development of children’s and adolescents’ brains, what is essential is not indirect experience via a screen, but interactions in the real world. Additionally, in order to grow healthy with a well-balanced body, it is critical to strengthen the musculoskeletal system and cardiorespiratory function by maintaining proper posture and exercising regularly. Every area of the brain, including the cerebrum, the cerebellum, and the brain stem, grows rapidly from birth to age 2 [16], which is why experts worry about children’s use of the internet and electronic devices, especially for those aged 2 and younger. Without proper guidance or direction, using smart devices at such an early age may negatively affect the physical and cognitive development of infants. During childhood, the frontal lobe, which is responsible for self-control and self-regulation, is not fully developed. Instead, what prevails in a child’s brain is the reward pathway, which focuses on momentary fun and the experience of a reward; this is why children may encounter difficulties in controlling themselves when using addictive smart devices and video games [17].

According to a 2016 study by the Korean National Information Society Agency, the size of the potential risk group for smartphone overdependence among young children (age 3-9) showed a 5.5% increase compared to the previous year, which was far more drastic than was observed for other age groups [18]. Experts advise that children aged 2 and younger must have restrictions placed on their use of the internet and electronic devices to ensure their healthy development [19]. In particular, children and adolescents need to be encouraged to participate in face-to-face interactions and group activities that require cooperation, so that they can develop age-appropriate social skills.

3.2 Parents need to reduce their smartphone usage

The more parents use smart devices, the more their children are likely to do so as well. Studies have demonstrated that when parents are at high risk for smartphone overdependence, their children are more likely to be at high risk as well (Fig. 10.3). It has been reported that while children at a high risk for smartphone overdependence are using smartphones, their nurturers tend to do other things, such as doing housework or resting [20]. If parents hope to limit the duration of their children’s smartphone use, they need to make efforts to reduce their own smartphone usage by engaging in physical activities or by playing with their children. Parents need to set an example first by not being absorbed with video games in front of their kids, and by staying away from media devices during meals and at bedtime.

Figure 10.3

Correlation between parents’ smartphone use and their children’s smartphone overdependence

(Adapted from Ministry of Science and ICT · National Information Society Agency [20])




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[1] Contributing associations:

Korean Academy of Addiction Psychiatry

The Korean Society of Medical Informatics

Contributing experts:

Young-Chul Jung, Department of Psychiatry, Yonsei University College of Medicine and Severance Hospital

Hee Man Kim, Department of Internal Medicine, Yonsei University Wonju College of Medicine and Wonju Severance Christian Hospital