In the fourth industrial revolution era of the 21st century, there has been increasing interest in the brain science. The recent Coronavirus Disease 2019 (COVID-19) pandemic has caused much fear due to the uncertainty, universality, and unpredictability of outbreaks. This fear is not limited to physical infection problems, but also includes threats to mental health, leading to negative psycho-emotional experiences such as corona blue or corona red with unstable brain function [1, 2]. The coronavirus has affected everything in our day-to-day lives including work, school, routines, and mental health.

In the COVID-19 situation, 41.9% of the general public has experienced uncomfortable thoughts about the coronavirus. More than a third (35.6%) reported feeling nervous or anxious when watching the news about COVID-19 on social networks [3]. Cao et al. [4] found that 24.9% of medical students were afflicted with anxiety due to the COVID-19 outbreak, while Park et al. [5] reported that late adolescents experienced more anxiety about COVID-19 infection than Ebola or H1N1 virus infection.

Despite active psychological quarantine support, late adolescents are concerned about the long-term impact of blind spots. Khan et al. [6] and Pedrosa et al. [1] reported that late adolescents are vulnerable to a psychological impact due to major changes in their routine school life, since schools were temporarily closed, and events such as study exchanges and graduation ceremonies were postponed. Many students lost their part-time jobs due to the closure of local businesses [4, 6].

Late adolescents are also vulnerable from a developmental perspective. Late adolescence is when cranial neural network development and atrophy, called pruning, occur simultaneously. The pruning of synapses starts in adolescence and continues until the late 20s [7]. Brain maturation, the rewiring process in the prefrontal lobe, is not complete until approximately 25 years of age [8]. Therefore, college students in late adolescence experience difficulties in emotion regulation because of the instability of the brain [9]. Petanjek et al. [7] revealed some changes in brain network connectivity related to aging from middle to late adolescence and sensitivity to stress response hormone regulation in the brain [10]. Therefore, mental health problems and school maladjustment may occur because of a lack of self-regulation [11]. When stress is prolonged or sustained as with COVID-19, the stress response is initiated in the actual brain system.

Despite great attention to self-regulation in previous research, there has been minimal research regarding a brain science approach in nursing intervention. The self-regulation mode is the ability to respond and control the intensity and frequency of verbal and physical activities during adolescence. If emotions are not properly controlled, internalization problems such as anxiety and anger arise, and externalization problems such as impulsivity and delinquency aggression can occur [11].

In particular, anxiety [12] and impulsivity [13] were found to be heightened in adolescence, and emotional distress was exacerbated through rumination [14]. However, meta-mood or self-regulation abilities might support effective emotion regulation [15]. Therefore, to measure the effects of Electroencephalogram (EEG) biofeedback training from the perspective of neurocognitive development in late adolescence, both emotional characteristics and strategic methods for helping emotion regulation were selected as dependent variables.

Uncertainty and fear of coronavirus infection can manifest as negative reactions such as infection anxiety, impulsivity, and anger [2]. High anxiety about the COVID-19 pandemic includes problematic responses that can cause impulsiveness or even anger that can eventually develop into self-destructive behavior in adolescents [13]. Impulsivity is usually defined as inappropriate and careless behavior without planning [16]. In a prolonged stress situation, people may take risks or make hasty decisions. They may also react haphazardly to internal and external stimuli without considering consequences. As a result, impulsivity can act as a factor in intrinsic or extrinsic problems. Anger also starts from resentment related to the inconveniences of daily life caused [17] by social distancing or social disconnection and can cause emotional-behavioral problems. Anxiety, impulsivity, and anger rumination [14] are trigger factors in late adolescence due to unstable brain function. Behavioral control of self-regulation requires great cognitive and executive functions in the prefrontal cortex [8]. Thus, nursing interventions related to brain science to control anxiety, impulsivity, and anger in late adolescence are necessary.

Meta-mood is the ability to check and adjust one’s emotions on a reflective level through cognitive thinking [18]. Emotions related to experiences evoked by important events are multifaceted in terms of behavior and physiology. Controlling negative emotions in a COVID-19 situation requires clarity of emotion recognition in a meta-mood. Self-regulation ability is the process of controlling human functions and states by the self [14]. In general, two modes are discerned: adaptive goal-oriented self-regulation and maladaptive volitional intentional inhibition mode [19].

EEG biofeedback training, a self-regulation intervention based on brain science and also referred to as neurofeedback training, uses cranial nerve plasticity. Neurofeedback focuses on the central nervous system to improve neuroregulation and the stabilization of brain waves [20]. Neurofeedback training strengthens self-regulation ability by repeatedly training while seeing and hearing feedback in real-time using an operant conditioning paradigm. First studied by Berger [21], EEG was used to directly diagnose brain problems and detect brain dysfunction. The previous scientific literature shows that quantitative EEG (QEEG) is a very reliable and reproducible [22] approach when normative databases (Z-score) of the homeostasis of the human brain are used.

Self-regulation is a high-level executive process in the frontal lobe of the brain involving planning, inspection, monitoring, evaluation, and cognitive control as core components of emotional control [23]. Furthermore, there is a significant relationship between brain executive function and self-regulation [24]. In particular, ambiguity and uncertainty about new viral diseases, such as COVID-19, can trigger abnormal brain function in the cognitive, neurological system.

Since the 2000s, several previous studies have revealed the therapeutic effects of neurofeedback as an independent nursing intervention on fatigue and stress perception and immune response in nursing students [25], stress and depression [26], brain function in high school students [27], and autonomy control in patients with alcohol use disorder [28] in the domestic nursing field. To optimize the relief of emotional distress, such as anxiety about COVID-19 infection, impulsivity, anger rumination, meta-mood, and self-regulation ability during the COVID-19 pandemic, we analyzed the emotional characteristics of late adolescents, also referred to as digital natives because they have been exposed to the Internet since birth.

Therefore, in this study, we aimed to investigate the effects of EEG biofeedback brain computer interface (BCI) system-based interventions and to develop educational program content or standard practice guidelines for using EEG biofeedback training based on brain science in various clinical practices or nursing research areas as an independent nursing intervention in the COVID-19 pandemic situation.

In this study, we investigated whether EEG biofeedback training is effective in emotion regulation for late adolescents as an independent nursing intervention in the COVID-19 pandemic. EEG biofeedback training intervention is the basis of the cognitive neuroscientific approach to explore brain function to reveal the essence of human emotion regulation.

The first hypothesis was partially supported. The results revealed that neurofeedback training is an effective tool for emotion regulation. After neurofeedback training, the self-regulation ability of the experimental group increased. This result was consistent with the findings reported by Choi and Park [31] and Barrows and Jacobs [39], who found a significant positive change in self-regulation in late adolescence. Self-regulation ability can be defined as the dynamic process of regulating and maintaining motivation, cognition, and emotion to achieve one’s desired goals [40]. In this study, both self-regulation and volitional inhibition modes showed significant effects after the intervention. Self-regulation ability can be seen as lowering the stress level and motivating and organizing adaptive behavior [41]. Kuhl and Fuhrmann [37] believed that thinking and planning in intentional memory occurs in the left lobe of the brain. In contrast, intentional memory controls goal maintenance and intuitive conventions in the right lobe of the brain to support positive emotions. Therefore, EEG biofeedback training can help control adolescents’ negative emotions elicited by the COVID-19 pandemic. The results confirmed that EEG biofeedback training could be an appropriate procedure for emotion regulation.

The pre-test scores of anxiety about COVID-19 infection were 3.67 in the experimental group and 3.64 in the control group. These findings are consistent with the results previously reported by Park et al. [5], who showed that university students’ anxiety was 3.70. The total sum of anxiety was 33.3, and it seemed that coronavirus-related anxiety was significantly higher than that of Ebola infection (13.92) and swine flu (22.87). This means that late adolescents have high anxiety about COVID-19 infection in their daily lives. Similar to several clinical reports on the effectiveness of neurofeedback training for anxiety disorder [42, 43], anxiety was found to significantly decrease from 3.67 to 3.13 after the intervention. Anxiety is caused by ambiguity or uncertainty about the present situation or future events. However, in the present study, we provided brain-based biological interventions such as learned relaxation methods to reduce anxiety and change their biomarkers using biofeedback with repetitive training that can enhance monitoring, concentration, and self-regulation. Therefore, neurofeedback training that combines methods of both mind-body medical intervention and nursing education intervention will have the advantage of reducing anxiety compared to providing accurate information only.

Furthermore, we found that cognitive impulsivity decreased significantly in the experimental group. These results contradicts the finding of Joo and Son’s [44] that game-addicted late adolescents have significantly reduced impulsivity. The level of attention and arousal increased by enhancing the SMR waves and decreasing theta. Although a previous study revealed that impulsivity gradually decreased [44], in our results, no significant differences between the two groups were observed after providing EEG biofeedback training. Therefore, it is recommended to increase the intervention period and sessions to 20 or more during the COVID-19 pandemic situation.

Angry afterthoughts significantly decreased after neurofeedback training only. Anger is a universal human emotion that usually arises from an overload of stress, such as in the context of the recent COVID-19 pandemic. Moreover, frustration and dissatisfaction due to social distancing or isolation in the COVID-19 situation may cause anger that starts from resentment due to school closure, suspension of school schedules, and changes in personal daily life routines, which were not the students’ faults. Furthermore, anger provides important energy for survival by eliciting the physiological motivation to cope with danger and protect ourselves from our environment and situations [45]. With additional nursing education on anger management, nurses can help adolescents learn to use functional anger, rather than dysfunctional anger.

The clarity of emotion in meta-mood showed a significant difference after neurofeedback training in the experimental group only. Emotions are multifaceted phenomena related to experience, behavior, and physiological changes. Meta-mood is the ability to check and adjust one’s feelings or emotions on a reflective level through cognitive thinking [18]. The clarity of emotional recognition is the basic ability to understand one’s own emotional state [18]. Control of negative emotions, such as anxiety and anger, in the COVID-19 situation, requires clarity of emotion recognition. A previous study on adolescents by Lee [46] revealed that adolescents who recognize emotions tend to use more adaptive emotion regulation. Furthermore, people with negative emotions have difficulty maintaining self-regulation in stressful situations and exhibit maladaptive behavior. For instance, Anttila et al. [47] noted that less preventive behavior was observed in individuals with a high level of negative emotions. In stressful situations such as COVID-19, the greater the difficulty in emotion regulation, the more inappropriate the coping strategies that can follow.

Only mood repair of the meta-mood showed a significant difference between the two groups after neurofeedback training. If people can better understand and express their feelings, they can better adjust their emotions through cognitive thinking in adaptive or functional ways [36]. The advantage of this study was that we provided individual protocols to increase the homeostasis of brain function using strategies regarding the participants’ attention to auditory and visual feedback during the intervention. Interest and motivation were generated through computer games with repetitive training sessions. The individuals in the experimental group used self-learning and self-evaluated their improvement with a computer monitor during the training process. The goal of training interventions was to train the study participants to normalize spectral distribution by using the Z-score of normal brain function since training one area of the brain can affect a wide area of brain functions.

The second hypothesis was partially supported. Electrodes placed on the midline sagittal plane of the skull (Cz and Pz) and used mostly for measurement points showed good results. The Cz region refers to the midline central region of the head, where the sensory motor lobe is located, and Protocol 1 is used to enhance the SMR and reduce theta and high beta waves. The sensory-motor zone of the Cz region is a structural and functional center of the cortex with a higher density of primary system innervation, which has a greater influence, reduces artifacts during training, and can enhance SMR waves to enhance attention with relaxation. The results revealed that enhancing SMR to concentrate and recognize emotions can help develop proper coping mechanisms.

The location of Pz in the international 10~20 system is an important part of the parietal or occipital regions, and it is normal if the alpha waves are higher in the middle line posterior to the head than at the front [30]. An increased alpha wave was observed on the posterior midline scalp electrodes (Pz). Protocol 2 was used to enhance alpha and reduce theta and high-beta waves in the Pz region. The hyperactivity of alpha waves in the frontal lobe usually indicates depression or difficulty concentrating. This suggests that the frontal lobe is too relaxed and does not function properly. Although neurofeedback training usually has a significant improvement effect on reducing anxiety [48], Lipp and Cohen Kadosh [49] recommend using additional neurofeedback training with cognitive behavior therapy or other interventions. Therefore, combined effective intervention strategies are needed to develop interventions for late adolescents in the COVID-19 pandemic situation.

If more information is repeatedly provided every day because of the continuously changing prevention protocol for COVID-19, it may further increase anxiety [3]. EEG biofeedback is a suitable way to learn how to control anxiety and emotion regulation easily. Computer games based on brain science are very easy to concentrate on and can be used to monitor the changes in physical responses from negative emotion reactions in EEG biofeedback training and to check the improvement of brain function, which changes little by little every session through repeated training with rewards and suppression of biofeedback training.

Despite the observed positive effects of the tested neurofeedback training, the present study has several limitations. First, convenience sampling was used due to the regular collection of individual brain waves by monitoring each time during 10 sessions. In future research, we strongly recommend a controlled study with larger samples and additional sessions on a regular basis.

Despite these limitations, this study contributes to the available research by pre-evaluating an individual’s resting basis of state QEEG before intervention to find individualized protocol strategies with a three-band protocol by inhibiting and rewarding brain waves. This training is a type of cognitive-behavioral therapy that uses the operant conditioning principle [50]. In other words, it seems that relaxation and concentration for self-regulation, which gives and receives feedback in real-time brain function, helps solve emotional distress from the COVID-19 pandemic.

Furthermore, our results are meaningful because they confirm the effects of EEG biofeedback intervention on various emotional problems in COVID-19 for psychiatric mental health nurses and nurse practitioners. The intervention we tested was noninvasive and non-pharmacological. Furthermore, by combining neurofeedback and other psychological nursing interventions, long-term intervention should be recommended in late adolescents who need to regulate emotional distress during the COVID-19 pandemic situation.

In this study, we used a brain science approach as an independent nursing intervention for late adolescents facing the COVID-19 pandemic to evaluate the effects of a neurofeedback-driven QEEG-based computer game. Each study participant not only performed tasks related to each game but also kept their brain waves at the optimal level while receiving visual and auditory feedback on their own brain functions. The results confirmed that emotional problems could be solved by EEG biofeedback training, suggesting that neurofeedback training can be used by nurses or nurse practitioners as a mental health intervention. Additionally, this intervention can be effective for clinical nurses suffering from fatigue elicited by the prolonged COVID-19 situation. Our results demonstrate the ability of a neurocognitive approach to improve emotion regulation in late adolescents.