The increasing popularity of Social Networking Sites (SNS) across global society has been paralleled by increasing concerns regarding Problematic Social Networking Sites Use (PSNSU), a multifaceted condition characterized by impaired control over SNS-related behaviors resulting in continued use despite negative consequences (Griffiths, 2013, Musetti et al., 2021). Despite the absence of a consensus on its clinical characterization (Casale, 2020, Moretta et al., 2022), PSNSU can be conceptualized on the basis of multiple approaches: i) Five of the nine DSM-5 diagnostic criteria (i.e., preoccupation or obsession, withdrawal, tolerance, loss of control, loss of interest, continued overuse, deceiving, escape of negative feelings, functional impairment) for disorders due to addictive behaviors met within a year; ii) severity of functional impairment; iii) specific psychological mechanisms; iv) time spent online (Musetti et al., 2022, Wegmann et al., 2022). Of note, it has been also proposed that Caplan’s model of generalized pathological internet use (Caplan, 2002, Caplan, 2010) may provide a conceptual basis for understanding the PSNSU. In this context, PSNSU has been described as characterized by some specific symptoms, such as Preference for Online Social Interaction (POSI), using the SNS for mood regulation, cognitive preoccupation related to the use of the internet, compulsive use, and negative outcomes (Caplan, 2010, Casale and Fioravanti, 2015, Casale and Fioravanti, 2017, Marino et al., 2017, Moretta and Buodo, 2018; Musetti, Grazia, et al., 2022; Ryan et al., 2014). Specifically, using SNS to regulate mood and POSI are associated with difficulties in regulating SNS use, which, in turn, predicts negative outcomes of SNS usage in daily life (Assunção and Matos, 2017, Moretta and Buodo, 2018). Importantly, using SNS for mood regulation appears to have a greater impact than POSI on negative outcomes of PSNSU (Moretta & Buodo, 2018). Thus, PSNSU has been interpreted as emerging from the need to compensate for low social competencies (Wegmann & Brand, 2019) and/or to cope with negative affect in the absence of effective emotion regulation strategies (Hormes et al., 2014, Wegmann and Brand, 2016). Noteworthy, despite the consequences of negative outcomes triggered by PSNSU, the overall understanding of their underlying mechanisms as possible intervention targets remains far from complete.

Among the negative outcomes of PSNSU, a reduction in sleep quality (i.e., the satisfaction of one’s overall sleep experience) and subsequently poor mental health outcomes have been largely documented (Gupta and Sharma, 2021, Kokka et al., 2021, Tandon et al., 2020). Specifically, in university students, high subjective distress and aversive mood states including anger, contempt, disgust, guilt, fear, and nervousness have been associated with sleep disturbance via fear of missing out, the desire to stay continually connected with what others are doing (Li et al., 2020). Moreover, pre-sleep worry and fear of missing out could be linked to sleep disturbance in adolescents (Scott & Woods, 2018). Importantly, worse school performance linked to PSNSU may result from poor sleep habits in youth (Vernon et al., 2015). Overall, these findings highlighted that subjective distress and fear of missing out can be two of the main processes related to poor sleep quality. Another potential mechanism leading to poor sleep quality in PSNSU could be blue light emitted through technological devices used before bedtime leading to suppression of melatonin. Suppressing this hormone is the basis of neuropsychological arousal and thus, alterations in circadian rhythm affecting sleep latency and duration (Chang et al., 2015). Of note, reduced mood regulation capacities have been proposed as a primary mediator in explaining the relationship between negative affect, problematic use of the internet, and sleep-related symptoms (Guerrini Usubini et al., 2022). In addition, Musetti, Gori, et al., (2022) found that psychological stress and emotion dysregulation sequentially mediated the positive association between problematic online pornography use and insomnia. However, no study to our knowledge has yet investigated whether using PSNSU for mood regulation, a feature of PSNSU, would specifically characterize individuals with poor vs. good sleep quality and who seek alternative emotion regulation strategies.

One of the unpleasant subjective feelings that received considerable attention among researchers studying PSNSU is loneliness (i.e., the subjective feeling of social isolation resulting from a discrepancy between desired and actual social relationships; Moretta and Buodo, 2020, O’Day and Heimberg, 2021, Perlman and Peplau, 1981). Specifically, it has been suggested that in modern society the use of SNS increases loneliness and isolation. The reasons for this may be found in the displacement hypothesis which argues that people displace offline relationships with online ones. However, online communication lacks the quality of face-to-face human relationships and in turn, may lead to loneliness (Kraut et al., 1998, Turkle, 2011). Moreover, the model of compensatory internet use posits that negative life situations and feelings (e.g., loneliness) can give rise to a motivation to use SNS to alleviate negative affect. In this scenario, high loneliness levels might be a vulnerability factor leading to PSNSU (Kardefelt-Winther, 2014). At the same time, others argued that the use of SNS may reduce loneliness by enhancing existing relationships and favoring new ones (Gross, 2004, Valkenburg and Peter, 2007). A recent theoretical model posits that the relationship between loneliness and SNS use is bidirectional and dynamic with loneliness increasing when using SNS as a way to escape offline social relationships and decreasing when using SNS as a way to expand one’s social network/strengthen existing relationships (Nowland et al., 2018).

Of note, loneliness has been also correlated with lower to poor sleep quality. A systematic review and meta-analysis found loneliness to be medium-sized (cross-sectionally) related to impaired sleep quality and insomnia symptoms (Griffin et al., 2020) supporting the hypothesis that loneliness might be one possible factor leading to poor sleep quality. Interestingly, a recent review (Alonzo et al., 2021) reported longitudinal evidence suggesting poor sleep quality and frequent sleep disturbances as mediators of the association between poor mental health outcomes and PSNSU. Furthermore, a study investigating the effects of a 1-week vacation from SNS found that limiting SNS use has benefits for both wellbeing and sleep quality, with changes in sleep quality being responsible for the relationship between limiting SNS use and wellbeing (Graham et al., 2021). Given the negative relationship of sleep quality with both loneliness and PSNSU, it can be hypothesized that individuals with poor sleep quality are characterized by specific PSNSU symptoms related to loneliness, a key factor in the onset of depression and other common mental health problems (Mann et al., 2022). However, despite the evidence of a relationship between mental health, PSNSU, and sleep quality, to the best of our knowledge studies investigating whether specific PSNSU symptoms are related to loneliness, in individuals with poor vs. good sleep quality are lacking.

As for gender differences, previous research has shown that loneliness seems to be higher among men, compared with women (Barreto et al., 2021). However, this finding is contrary to those from some other studies, where loneliness level was reported to be higher among women than among men (Nicolaisen & Thorsen, 2014). These inconsistencies among studies may occur largely because gender differences in loneliness seem to be environmentally (e.g., social norms, cultural influences) rather than genetically determined (Boomsma et al., 2005). In this sense, changes in life patterns regarding the use of SNS might have an important role in determining gender differences in loneliness. In turn, gender differences in PSNSU can help to understand gender differences in loneliness. Indeed, it has been argued that women are socialized to develop a larger/more active social network that may works as protective factor from loneliness (Barreto et al., 2021). At the same time, it has been shown that given to gender stereotypes, men are more reluctant than women to express feeling lonely (Borys & Perlman, 1985). It can be hypothesized that men can use SNS for compensating their restricted social capital. However, at the same time engaging in SNS surfing may be perceived by women as a mean of further enlarging social connections leading to POSI. In turn, POSI may exacerbate social avoidance and reinforce SNS-mediated relationships, a cognitive symptom of PSNSU (Casale et al., 2013; Lee & Stapinski, 2012). In the context of PSNSU, it has been recently shown that men and women are characterized by different core symptoms, i.e., salience and conflict, respectively (Wang et al., 2022). Specifically, in men, cognitive salience of SNS use (i.e., preoccupation with SNS use and engaged in to the neglect of everything else; Griffiths, 2005) would progress into tolerance behaviors. Conversely, in women the conflict caused by excessive SNS use (i.e., negative outcomes caused by excessive SNS use including the compromising of relationships, occupation, and/or education; Griffiths, 2005) would be related to less control in using SNS (Wang et al., 2022). This finding may suggest that deficient self-regulation (in men) and negative outcomes of using SNS (in women) may have negative consequences on users’ social capital leading to loneliness feelings. A systematic review studying current trends in the literature on problematic internet use showed that men are more susceptible to the generalized form of problematic internet use. On the other hand, women seem to be at more risk than men on PSNSU symptoms or severity (Baloğlu et al., 2020). However, reasons underlying gender-related specific pattern of use remain to be clarified. Importantly, a recent meta-analysis found that there was no moderation effect for gender on the relationship between PSNSU and mental health (Shannon et al., 2022). The authors argued as a possible explanation that studies included in the meta-analysis did not specify if they assessed biological sex and they suggested further research to provide more specific results for sex and genders allowing future meta-analyses to summarize this information more accurately. However, despite the importance of studying gender differences for their potential insights into the etiological and pathogenetic mechanisms of maladaptive behaviors and mental disorders and to improve preventive programs for both women and men, little is known about how men and women differ in the pattern of relationships between loneliness and PSNSU domains.

In light of these considerations, the present study aimed at examining relations between loneliness and PSNSU symptoms (i.e., POSI, mood regulation, deficient self-regulation, and negative outcomes), and possible moderating effects of gender for individuals with poor vs. good sleep quality. We hypothesized that (a) individuals with poor sleep quality would show higher levels of loneliness, greater POSI, higher use of SNS for mood regulation, as well as greater cognitive preoccupation and compulsive use, and negative outcomes of using SNS as compared with individuals with good sleep quality; (b) only in individuals with poor sleep quality, loneliness would be associated with higher SNS use-related problems; (c) as for gender differences in the relationship between loneliness, PSNSU domains and sleep quality, no a priori hypothesis was formulated given the presence of previous contrasting results.