In the last few years, smartphones have become one of the main parts of a person’s everyday life. Thanks to the range of applications and benefits they provide, these smart devices have become an indispensable aid in business, learning, entertainment, and everyday functioning. In addition, smartphones can also serve as a way of coping with stressful situations by providing a range of different contents [1]. Although smartphones significantly facilitate people’s daily lives, studies on negative correlations and consequences of excessive use of smartphones are worrying. Accordingly, Pera [2] stated that excessive use of these devices or their problematic use can leave negative consequences on the human brain and related psychological processes. He further explained that the problematic use of mobile phones was negatively linked to the psychosocial well-being of young people and affected their mental health. Some research confirmed that the use of smartphones, which can be considered problematic, is associated with the severity of depressive symptomatology and anxiety symptoms, lower self-esteem, perceived social support, and emotional dysregulation. Due to the growing involvement of smartphones in human life and their impact on various psychological processes, a relatively new phenomenon that is associated with smart devices, called nomophobia, has surfaced. It is a type of behavioural addiction to smartphones based on feelings of anxiety and restlessness or anxiety in situations where a person is unable to access a smart device and reach all the benefits it provides [3]. Yildirim and Correia [4] offered another definition of nomophobia as a fear of not being able to use smartphones and the various services they provide.

On the other hand, nomophobia can also be observed in terms of addiction, such as internet addiction or smartphone addiction. Proponents of this approach often define nomophobia as an addiction to online social networks, and they explain how people with intense levels of nomophobia perceive a smart device as a source of comfort and feelings of relief (like other addictive substances) [5].

Considering previous theoretical knowledge and definitions of nomophobia, nomophobia can be viewed as a disorder characterized by behaviours with different clinical characteristics; it can cause several psychological symptoms and implies a pathological fear that a person will not be able connect with new technologies [6]. In addition, nomophobia can be defined in terms of behavioural dependence but can also be viewed as situational phobia.

It is quite clear that smartphones are becoming more popular every day because of the many benefits they provide. According to the latest data, there are currently 6.37 billion smartphone users in the world, and that number will increase over the years [7]. Accordingly, it is logical to assume that the prevalence of nomophobia will increase with time as well, as it is based on the excessive use of smartphones. In a study among participants whose ages ranged from 17 to 29 years, the authors found that 71.5% of participants exhibited moderate levels of nomophobia and 8.5% severe symptoms of nomophobic behaviours [8]. Bodrožić Selak conducted the first research of Croatian population on this topic and concluded that students show moderate levels of nomophobia [9]. Gržan confirmed a slight increase in the severity of symptoms of nomophobia in a sample of Croatian students [10].

Young and Rogers found that more pronounced depressive symptomatology was associated with excessive Internet use [11]. It is possible that the basis of this connection is characteristics that characterize a depressed person, such as low self-esteem, lack of motivation, and the need for approval, which contribute to more frequent online communication and excessive use of the Internet. Similar findings were confirmed in other study, where a positive relationship between problematic smartphone use and depression was found [12]. In one of a few studies on this topic, Sharma et al. [13] found a significant positive relationship of nomophobia with depression. The same authors explain that there is a possibility that adolescents who express depressive symptoms more use social networks to reduce their levels of loneliness and to improve their self-esteem.

King et al. stated that participants diagnosed with panic disorder in situations without access to a smartphone experience more intense mental and physical symptoms [14]. It is possible that the use of mobile phones has a positive effect on people with panic disorder and alleviates the symptoms of a panic attack. Another study found that individuals who reported higher levels of anxiety were more likely to resort to online forms of communication to alleviate their own anxiety symptoms [15].

Ayar et al., in their study, tried to determine the relationship between nomophobia and type of social anxiety connected with body image, and they confirmed that people who experience higher levels of anxiety because of their body image and self-perception of their body achieve higher results on the nomophobia scale [16].

Bekaroğlu and Yılmaz stated that there is a correlation between nomophobia and symptoms of various negative psychological states such as anxiety and depression [17]. More specifically, it is possible that the fear of not being able to use smartphones intensifies the symptoms of stress, anxiety, and depression, but it is possible that individuals with the aforementioned symptoms are more susceptible to developing nomophobia.

Individuals who showed nomophobic behaviours experience more intense levels of stress in those situations where they cannot access a mobile phone [18]. The connection between nomophobia and stress can also be explained by the fact that smartphones often provide a way of coping with difficulties. Nomophobia can be a mediator between different behaviours and habits associated with smartphone use and stress, anxiety, and depression. More specifically, individuals who spend more time searching social media experience higher levels of nomophobia and then more severe symptoms of the distress factors [9]. The connection between nomophobia and stress can also be explained by the fact that smartphones often act as a means of coping with difficulties. When a person experiences stress, he/she often reaches for a smartphone and all the benefits it provides, and this can lead to excessive and problematic use of these modern forms of technology, which are at the root of nomophobia [19].

Research conducted on a sample of adolescents found a positive relationship between nomophobia and loneliness in which nomophobia was a significant predictor of loneliness [20]. Furthermore, the same authors explain that individuals who do not have access to their own smartphone experience a feeling of loneliness, which is based on fear of not being able to communicate and socialize with others [20]. Yildiz Durak also found that there is a positive relationship between nomophobia and loneliness and added that people who have difficulty communicating one-on-one are more likely to resort to online communication, which can remove them from the real world, and as result, loneliness occurs [21]. This can then be manifest in the form of negative emotions, which can result in distance from the social environment and reduced motivation. One research found that those adolescents who spend more time behind the screen of smartphones experience higher levels of anxiety and loneliness and consequently show higher levels of nomophobia [22].

It can be assumed that individuals whose smartphone use can be characterized as problematic experience more serious psychological problems precisely because of poor, maladaptive strategies of emotional regulation [10]. Engelberg and Sjoberg found that Internet addicts are worse at recognizing and decoding emotions [23]. In addition, individuals who have difficulty coping with negative emotional states often turn to the Internet and social media, which can potentially lead to addictive behaviours and ultimately result in pronounced levels of nomophobia [24].