Low self-efficacy, positive outcome expectancies, and impulsivity have been identified in excessive SNS users (8). Among 8,912 college students across seven countries (U.S., Canada, Spain, England, Argentina, Uruguay, and South Africa) high ruminating thoughts have accounted for major depressive and social anxiety symptoms (31). Several studies have shown an association between low self-esteem (32, 33) and fear of negative self-evaluation (34) anxiety (35) and problematic SNS use.

Problematic SNS use was linked with cyberbullying and cyber victimization of university students (36, 37). Students who reported that their upbringing style as inconsistent and unbalanced and those who showed an aggressive trait had higher scores of problematic SNS use (38). Child emotional abuse, indicated by deficient self-other differentiation and impaired reflective function was also associated with problematic SNS use (39). Stress, impulsiveness and reduced inhibitory control contributed to problematic SNS among lower socio-economic families in China (40). Finally, lower emotional intelligence predicted perceived stress, which contributed to depressive symptoms and problematic SNS use (41).

Problematic SNS use was also associated with social comparison which is linked with stress and impaired wellbeing) (42). “Peer phubbing” (the act of ignoring other people in the context of social contact by paying attention to his/her phone instead of focusing on the person directly in his/her company) correlated with problematic SNS use (43). Furthermore, social anxiety mediated the association between “peer phubbing” and problematic SNS use, particularly among undergraduates with family financial difficulties (43). Finally, “peer phubbing” was associated with loneliness and problematic SNS use (44).

Emotion recognition deficits among individuals with problematic SNS use were demonstrated on the Reading the Mind in the Eyes Test (RMET) (45). A following study has shown that faulty meta-cognitions (like worry, superstition, punishment, beliefs about responsibility, and cognitive monitoring) but not emotion recognition predicted problematic SNS use in adolescents (46).

Female adolescents reported higher scores of body shame, social physique anxiety and problematic SNS use (47). Awareness and internalization mediated the association between body dissatisfaction and problematic SNS use (48). Depression and anxiety mediated the relationship between perceived stress and problematic SNS use and this relationship was moderated by psychological resilience, but not by social support (49). Negative body image correlated with frequency of SNS use and it was enhanced by exposure to appearance-related content on the Internet. Furthermore, negative body image or body shame was indirectly associated with adolescents' problematic SNS use (50). Finally, high levels of self-reflection was a protective factor against problematic SNS use among adolescents. Adolescents with problematic SNS use tend to have low exploration of self-identity and in crisis they consider alternative commitments instead (51).

A meta-analysis has reported that depressive symptoms weakly correlated with time spent using SNS and intensity of SNS use (52). However, depressive symptoms moderately correlated with problematic SNS use, and it was not moderated by other factors like age or gender.

The urge to use SNS was associated with handling boredom rather than increase positive emotions or reduce negative emotions (53). Others stress the importance of social rewards like “likes,” social comparisons and connection with other people rather than motivations based on enjoyment and negative power (54). There is supporting evidence that young people tend to use SNSs to enhance their external expectations of having a large network size rather than internal expectations for subjective wellbeing (55). Finally, young adults who used social media for 2 h or more daily, increased perceived social isolation compared with those who use it for < 30 min each day (56). Similar associations were reported in middle-aged and older adults (57). It has been suggested that people who have reduced off-line social experiences and are highly influenced by social media tend to have unrealistic self-perceptions.

In summary, problematic SNS use has been associated with internal emotional factors like depression and anxiety, aggression and negative body image and external social motivations.

Emotional states and stress mediated the association between executive function, and problematic SNS use among Chinese female college students (58). There were no differences between problematic and non-problematic SNS use groups in cognitive flexibility and inhibitory control aspects of Executive Function measured by performance on the Wisconsin Card Sorting Test (WCST) (20). Categories achieved and number of perseverative errors correlated with scores Social Media Addiction (20). Finally, a study of inhibitory control mechanisms together with event-related potentials (ERPs) using an SNS Go-No Go task showed no performance differences between problematic and non-problematic users (59). However, there was an indication of larger N1 amplitude following SNS images than control images and a larger N2 amplitude and smaller NoGo-P3 amplitude in excessive users. These findings may suggest inefficient allocation and monitoring of resources and problems inhibitory control mechanisms (59). In summary, there is little evidence that problematic SNS use may lead to impaired flexibility of inhibitory control mechanisms, though there may be ERP evidence for late inhibitory control (unsupported by behavioral data).

It has been suggested that problematic social media use has been associated with FoMO in order to serve and compensate for individuals' social needs (60). FoMO mediated the relationship between the fear of a negative and positive evaluation and social use of the smartphone (60). FoMO and withdrawal ratings were higher among participants with 72 h of restricted access to smartphones compared with those without access to smartphones (61). FOMO also predicted excessive smartphone use by female WhatsApp users (62) and it was associated with the use of smartphones by American undergraduate students for social purposes (63). FoMO mediated the relationship between depression and anxiety and the severity of problematic smartphone use. This finding suggests that individuals experiencing social anxiety who desire social contact are likely to use the smartphone as an avoidance mechanism (63).

A survey of college students has found that greater social activity is a positive predictor of addiction to the social media application Snapchat (64). Among young adults who use Facebook, FoMO, dysfunctional cognitions, and distress predicted problematic SNS use (65). FoMO and rumination mediated the connection between social anxiety and problematic Facebook use (66). FoMO also played an important role in increased sensitivity to stress which is associated with neglect and problematic SNS use, and these in turn were associated with negative emotions (67). Finally, FoMO mediated the association between mental health and symptoms of Internet Use Disorder (IUD) (68).

The evidence on the relationship between attachment and problematic SNS use is scarce. The association between anxious attachment and problematic SNS use was mediated by FoMO and online social support, and online social support negatively mediated the association between avoidant attachment and problematic SNS use (69). A recent review has suggested that problematic SNS use negatively correlated with secure attachment and positively correlated with anxious attachment, but there was no clear association with avoidant attachment. Furthermore, the associations between problematic SNS use and attachment were mediated by individual and interpersonal variables (70).

Only few studies that have investigated the relationships between personality and problematic SNS use. Emotional stability, extraversion, and conscientiousness predicted Problematic Facebook use, among adolescents (71). Among the big 5 personality factors, agreeableness, conscientiousness, and self-liking negatively correlated with Instagram addiction (72). Furthermore, self-liking partially mediated the association between Instagram addiction with agreeableness and fully mediated the relationship between Instagram addiction with conscientiousness (72). Conscientiousness, Extraversion, Neuroticism, and Loneliness were predictors of Facebook Addiction. Neuroticism but not extroversion, had a positive correlation with problematic SNS use (73). Furthermore, frequency of status updates mediated the association between each personality trait and problematic SNS use. “Likes” mediated the association between extraversion and problematic SNS use and there was no effect for neuroticism (74). Finally, problematic SNS use correlated with the dark triad traits psychopathy, narcissism and Machiavellianism, and emotion dysregulation (75). Furthermore, emotion regulation played an important role mediating the association between dark triad traits and problematic SNS use (75). Specifically to narcissism, vulnerable narcissists reported a stronger preference for online social interactions and higher overall levels of problematic use of SNSs than grandiose narcissists (76). In summary, problematic SNS use has been associated with FoMO, attachment difficulties and certain personality characteristics like conscientiousness, agreeableness and neuroticism. There is contradictory evidence regarding extraversion and some evidence for an association with narcissism.

Few studies have explored the effects of problematic SNS use on sleep quality and duration in adolescents and young adults. A negative correlation was reported between time spent on screen-based devices and sleep quality and quantity (77). Furthermore, higher rates of insomnia, reduced sleep duration, later sleep onset and problems in sleep efficiency and evening screen time were reported among students who also showed similar patterns of sleep problems together with poorer academic achievements, reduced life satisfaction and depression (78). Among young adults in Italy, problematic SNS use was not directly associated with poor sleep quality and it was mediated by depression and stress (79). A majority of Czech adolescents use SNS before bedtime, 20% eat dinner while using SNS, about a third use SNS continuously, SNS use is associated with alcohol use and parental restriction can reduce problematic SNS use (80). Self-reported screen time and symptoms of withdrawal correlated with problematic SNS use, stressing the addictive properties of SNS use among adolescents (81). Finally, problematic SNS use was linked with male and female sexual difficulties (82). In summary, there is evidence that problematic SNS use is associated with reduced sleep quality and quantity, longer sleeping latency and more sleep disturbance and some evidence for sexual problems.

The go/no-go paradigm was used in 20 Facebook users who responded to Facebook and traffic sign control stimuli in functional MRI (97). There was a positive correlation between Facebook go trials and addiction scores but there was no association between inhibitory mechanisms and addiction scores. These findings have indicated that Facebook addiction shares some neural features with substance and gambling addictions, related to inhibitory-control brain mechanisms (97). Problematic SNS use was associated with reduced gray matter volumes in the amygdala but not in the nucleus accumbens in twenty social network site (SNS) users (98). The authors have argued that these alterations indicate impulsivity thus resemble other addictions. Furthermore, they have found a normal gray matter volume in the Anterior Cingulate Cortex (ACC) which suggests unimpaired inhibition mechanisms (98). Montag (99) have recorded actual Facebook use of 62 participants on their smartphones over the course of 5 weeks and they have reported that higher daily frequency of checking Facebook on the smartphone correlated with smaller gray matter volumes of the nucleus accumbens, suggesting that Facebook use has rewarding effects on the brain. An MRI study of social media users showed a negative correlation between gray matter volume of the insula with problematic SNS use symptoms that was mediated by delay discounting, an indicator of impulsivity (100). Symptom severity of problematic SNS use correlated with attentional impulsivity but not with executive function or inhibitory control of SNS-related cues (101). Finally, a study has investigated social anxiety-related inhibitory control comparing individuals who are addicted to gaming, problematic SNS users, and control participants. They have used a Go/no Go task with emotional words and the Emotional Stroop Task in fMRI (102). IGD participants showed impulsivity, social anxiety and impaired emotional competence, however there were no between group differences in performance of both tasks. During interference of socially anxious words there was decreased middle and superior temporal gyrus activity in gaming addicted participants compared with problematic SNS users (102). In summary, there is evidence that problematic SNS use is associated with impaired inhibitory mechanisms and reduced gray matter in several brain structures such as the amygdala, nucleus accumbens and the Insula. There is some evidence for impulsivity in these users but it is based on correlation and not on group differences.

A short-term abstinence intervention program based on Cognitive Behavior Therapy (CBT), has treated 65 clients with problematic SNS use. They had sessions of over 2 h breaks from social media for 2 weeks, compared with a control group that has used social media as usual. Intervention had a positive effect on emotional wellbeing, behavioral and cognitive function during abstinence and afterwards. These findings suggest that CBT-based short-term abstinence intervention can be useful to improve problematic SNS use (103). There is also preliminary evidence that “Social Media Detoxification” among university students can increase positive mood, reduce anxiety and improve sleep during and immediately after detoxification (104).