Anxiety, depression, stress, and other mental health issues have gradually become more prominent due to society's accelerated pace and fiercer competition in various fields. A survey showed that 14.97% of Chinese adults suffered the high-risk psychological disorders [1]. In recent years, mental health issues have caught much attention and become a long focus in psychological research. Poor mental health can cause a series of effects, such as physical health problems, interpersonal problems, cognitive states, and even extreme behaviors such as suicide [2–5]. Therefore, researchers have concentrated on figuring out the psychological mechanisms underlying mental health issues including depression, anxiety, and stress, as well as their causes. This has helped to advance the creation of effective therapeutic strategies.
A robust impact on mental health by fear of missing out (FoMO) was verified by many researchers recently [6, 7]. FoMO is a diffuse anxiety that occurs when individuals fear missing out on the positive experiences of others [8, 9]. Numerous research has discovered a connection between mental health and FoMO. For example, FoMO was positively correlated with depression and anxiety [6, 10] and significantly predicted stress [11]. Individuals with high levels of FoMO were more likely to suffer from alcohol abuse [12] and sleep disorders[13]. FoMO also decreased well-being [14] and life satisfaction [9]. Overall, existing research consistently shows that FoMO has a negative impact on mental health.
With the deepening of FoMO research, solitude behavior as a strong predictor of FoMO was discussed [15]. Chen et al. proposed that solitude behavior refers to a state in which individuals have no information and emotional communication with others when they are conscious [16]. Dhir et al. argued that individuals who miss out on fear always expect to be aware of the activities of others on a continuous basis [17]. It can be assumed that individuals in solitude are more likely to have a high FoMO. This has been confirmed by previous research, with Lai et al. finding that individuals with higher levels of loneliness had more severe FoMO on important information [18]. Bernard and Barry & Wong both found a significant relationship between loneliness and FoMO [13, 19]. Cheng also pointed out that loneliness had a direct positive predictive effect on the FoMO in an adolescent study [20]. Thus, this means that solitude behavior may activate the FoMO. Combined with the fact that FoMO negatively affects mental health, it is logical to assume that there may be a mediating mechanism from solitude behavior to FoMO and then to mental health.
Although existing studies have shown an association between solitude and FoMO, a review of existing research reveals that the increased FoMO in solitary individuals is primarily associated with increased feelings of loneliness. The motivation for solitude as an episodic behavior may vary widely. Nicol divided solitude behavior into self-determined solitude and non-self-determined solitude [21]. Chen et al. suggested that solitary behavior can include four types of behaviors resulting from different causes or motivations, namely positive solitude, eccentricity, social avoidance, and loneliness [16]. Positive solitude refers to the ability to enjoy independent activities. Eccentricity is a personality trait in which people feel comfortable being alone and usually fail to maintain good interpersonal relationships with others. Differing from positive solitude, eccentricity is sometimes accompanied by passive solitude. For social avoidance, interpersonal scenarios make individuals feel fearful and anxious, so they choose to avoid social situations to alleviate negative emotions. Loneliness is a subjective experience that arises when interpersonal needs cannot be met and often produces negative experiences when alone. Positive solitude and eccentricity are self-determined, whereas social avoidance and loneliness are non-self-determined. Lu et al. found that individuals can have four solitary behaviors at the same time, only the high and low levels of the four solitudes differ [22]. It was evident that solitary behaviors have complex motivational components, and the relationship between these complex components and fear of missing out and mental health remains unclear.
According to the Self-Determination Theory, the healthy development of individuals depended on the satisfaction of three basic needs: autonomy needs, competence needs, and relatedness needs. Among them, Relatedness needs refer to those needs that are satisfied by establishing social relationships with others [23]. FoMO occurred when an individual's interpersonal needs were not met [8, 24]. The study found that frequent use of social media kept people in a constant state of connectedness, which in turn increases the FoMO [24]. Milyavskaya et al. noted that FoMO that arises when individuals carried out activities with other people is lower than individuals interacted with their natural environment [11]. FoMO may increase if association with others cannot be maintained. Accordingly, this study hypothesized that individuals who exhibited solitude may have higher levels of FoMO when non-self-determined solitude is dominant, and conversely no association with FoMO when self-determined solitude was dominant.
In summary, this study intended to investigate three main questions: (1) how solitude behavior was related to f FoMO and mental health; (2) whether FoMO played a mediating role in the relationship between solitude behavior and mental health; and (3) whether there were differences in the effects of the four different types of solitude on mental health through FoMO.