Quality of sleep is known to have a pronounced effect on the health of children and adolescents [1–3] Sleep disorders can trigger to various abnormalities, both somatic and neurological [4, 5]. Moreover, sleep quality also affects adaptation of children to the educational process [6].

As confirmed by a number of Russian and foreign studies, use of digital devices (DD) can negatively affect various aspects of health [7–23]. An important component of the negative impact of DD is the blue light emitted by LEDs that are an integral part of screens [24–26].

Noise is another problem associated with DD that should be paid attention to in the context of a respective analysis effort [27].

In professional Russian publications covering hygienic aspects, screen time is commonly perceived as a monolith factor and not broken down into types. Foreign authors, on the contrary, differentiate between types of screen time and investigate them separately, writing respective reports. Screen time is categorized on physiological and functional grounds, i.e., there is an active (interactive) type thereof associated with games, social media, and learning, and a passive type of screen time, which involves watching TV and video content [28, 29]. Some papers point to the connections between various types of screen time and sleep disorders, and the degree of interactivity of the former was shown to influence the severity of the latter [30, 31]. From a practical standpoint, it is very difficult to limit a child's actual screen time, but it is much easier to control the devices they use. In this connection, this work attempts to assess the influence of various types of DD used for different tasks on sleep quality, one of the most significant factors characterizing the state of a child's nervous system.

This study aimed to investigate the influence of DD on the sleep quality of primary school children. 

METHODS

The survey was conducted in Zemskaya Gymnasium of Balashikha, and involved 333 parents of primary school children (ages 7–10 years). The questionnaire consisted of two blocks. The first block covered the purposes various DD were used for, and how often they were in use on the levels of a week and a day. The second block sought to investigate the quality of sleep, with questions about complaints such as frequent waking up, nightmares, and sleep disorders in general.

In the context of the study, we calculated relative risk (RR), odds ratio (OR), etiological fraction (EF). The risks were calculated at p < 0.05 (χ²). We used an online calculator available at https://medstatistic.ru/ for the purpose. For data gathering and statistical processing, Yandex Tables, StatTech (StatTech; Russia) software was used.

RESULTS

The study showed that 12.9% of children use a computer, 12.7% watch TV for more than three hours, 10.5% use mobile phones, and 6.1% of children use a laptop (tab. 1). Only 3.3% of primary school children use a tablet for more than three hours.

In the course of the study, we collected data on the weekly use of DD: 53.2% of children use a mobile phone daily, 47% of children watch TV shows, 25.9% of children use a laptop, 25.5% of children use a computer, and 18.8% use a tablet (tab. 2).

The study yielded data on the DD use-related risks of sleep disorders, nightmares and general abnormalities.

By (EF), the strength of casualty associated with DD was medium for the complaints of sleep disorders in general (RR = 1.87; 95% CI: 1.37–2.54; EF = 46%) (tab. 3).

We encountered a very strong causality between daily use of computer and nightmares by EF (RR = 4.75; 95% CI: 1.49–15.11; EF = 79%). A similar pattern was revealed for the tablet, which requires further study, since this device has a relatively large screen (more than 10 inches), but does not have the data input components like a laptop and a computer. Other results were only showing trends: over 3 hours of daily computer use and difficulties with falling asleep; 5–6 sessions with a laptop a week (or more) and nightmare complaints; 5–6 sessions with a tablet a week (or more) and nightmare complaints; watching TV in the evening and difficulties with falling asleep; watching TV shows in the evening and nightmare complaints.

DISCUSSION

Known publications that explore the hygienic aspects of use of DD rarely differentiate between types of digital addiction. Psychological literature, on the other hand, distinguishes between gadget addiction, fabbing, social media addiction, Internet addiction [32]. Since 2022, the ICD sees gambling addiction as an individual phenomenon.

From standpoint of a child hygienist, it is quite difficult to control the content that a child consumes, but from a practical viewpoint, parents can be recommended to control what kind of DD the child uses. An analysis of the influence of DD allows identifying smartphone as the source of addictions associated with gadgets, personal computer and laptop producing mainly gaming addiction, and TV as the device for consumption of video content in lengthy sessions.

If we consider playing on a smartphone and a desktop computer with a keyboard, mouse, subwoofer, and a screen with the diagonal exceeding 20 inches, it becomes clear that video game addiction is device-dependent.

Smartphone use patterns are characterized by shorter, one-time sessions, more frequent changes of activity, i.e., switching between applications, and a more pronounced multitasking.

At desktops, the level of control over the gameplay is higher, same as that of concentration and anxiety, and a single session lasts longer, since completing one level can last several hours.

Thus, it can be assumed that higher complexity of sensorimotor connections associated with playing on a stationary device translates into a deeper immersion in virtual reality.

At the same time, the type of video game addiction plaguing the younger generation has changed. Earlier, children preferred games that require hours of immersion (which can be conditionally compared with a second job), but nowadays, they favor simpler entertainment, when you can play several different games on the phone within 15 minutes. Thus, it may be concluded that this type of addiction takes features of clip perception, which is consistent with our reasoning. It can also be said that use of different types of DD brings forward different properties of the central nervous system: process mobility, balance, anxiety, excitability, etc.; this phenomenon should be investigated further.

At the same time, it is obvious that the addiction to TV shows and video content is also qualitatively different from the two addictions described above.

Currently, a popular concept is the triple-network model of the brain [33]: it includes the salience network (SN), the central executive network (CEN), and the default mode network (DMN). SN defines attention. It is activated when processing new information, and triggers fast, more superficial reactions, without great physiological investments. From the point of view of P.K. Anokhin's theory of functional systems, this network can hypothetically be compared with an afferent synthesis unit. For example, this system is activated when a person scrolls through the news feed and selects the content that interests him.

When the brain is thinking or playing a complex game, CEN starts working. This network is responsible for working memory and control [34], it is slower, requires more immersion in the process and imposes a greater physiological cost, which hypothetically can be described akin to the programming and control unit. 

There are reciprocal relationships between these brain networks: activation of one suppresses the activity of others.

Several authors have expressed similar views on information processing [34, 35]. SN dominates when a person surfs the Internet and tends to subconsciously practice clip perception; in such situations, CEN is not active. For information processing, including that peculiar to complex games, the brain activates CEN, which requires more physiological resources, and DMN is triggered for passive content viewing. Authors of [36] distinguish between interactive and receptive screen time, and point out that receptive screen time is based on DMN basis, which deactivates for interactive screen time. Thus, it is obvious that DMN deactivation triggers SN or CEN, depending on the type of interactive activity.

The type of DD is important from the practical point of view: it can be assumed that different DD are associated with domination of different brain structures. Devices with a large screen, keyboard and mouse activate CEN (programming and control unit) to a greater degree, and in the domain of smartphones (viewing clips, playing simple games, no complex control involved), it is less active, which, apparently translates into a lower physiological cost of the process and the absence of neuroticism. SN dominates in smartphone and clip perception scenarios, and the CEN and DMN networks are hypothetically not activated in such situations. TV watching involves DMN. The SN and CEN networks are not activated for TV, thus, there is no physiological costs involved, and no subsequent neuroticism and sleep disorders.

Thus, from the standpoint of the three-network model, it is CEN that can affect sleep since its activation means a more pronounced psychophysiological effect that translates into sleep disorders. The other two systems, SN and DMN, have no negative effect on sleep.

CONCLUSIONS

It was found that 53.2% of children use a mobile phone daily, 47% of children watch TV shows, 25.9% of children use a laptop, 25.5% of primary school children use a computer daily, and 18.8% use a tablet.

The study has shown that the parameters of sleep are influenced by type of DD as much as by the respective use patterns, which is explained by various types of digital addiction.

Thus, it has been shown that daily use of a computer and tablet increases the risk of nightmares in children. Using a laptop for more than an hour a day increases the risk of complaints of sleep disorders in general. According to the results of the study, smartphone use and watching TV are not associated with complaints of sleep disorders.

To prevent sleep disorders, children and adolescents should follow hygienic recommendations covering use of DD. It is especially important to limit the use of DD two hours before bedtime and just refrain from using such devices immediately before going to sleep.