Study Objectives: Bedtime procrastination (BP) is defined as going to bed later than intended despite absence of external reasons. This study investigated sleep and psychological factors associated with BP in young adults, and further compared how high and low BP groups spend their time over 24 h and also 3 h prior to bedtime using time use surveys. Methods: Young adults (N = 106) from the community were classified as either high (n = 54) or low (n = 52) BP group based on the Bedtime Procrastination Scale. All participants were asked to complete questionnaires on insomnia, depression, anxiety, stress, and chronotype, in addition to keeping a 7-day sleep diary and completing time use surveys over 48 h. Results: Participants were 61.3% female, mean age 22.7 (±2.89) years old. Individuals in the high BP group reported significantly more depression, anxiety, and insomnia, went to bed later, woke up later, and had more eveningness tendencies compared to the low BP group. Results from the time use surveys revealed that the high BP group spent significantly more time engaging in leisure and social activity with the majority of time spent using media over 24 h compared to the low BP group. Finally, the high BP group spent on average approximately 451% (or 61 min) more time per day on their smartphone 3 h prior to bedtime compared to the low BP group. Conclusions: Our results suggest that BP is negatively associated with sleep and mood, and should be considered a serious health-interfering behavior.

The behavioral inhibition/activation systems (BIS/BAS) have been considered to be predictors of Internet addiction, mediated by clinical variables such as anxiety and depression. However, resilience has been suggested as a protective factor toward Internet addiction, and certain sex differences in resilience buffering the effects of vulnerability have been reported. Thus, the aim of this study was to identify any role of resilience that might moderate the effects of BIS/BAS on Internet addiction through multiple clinical variables in boys and girls. A total of 519 middle-school students (268 boys and 251 girls, all 14 years old) were administered a questionnaire battery that measures Internet addiction, BIS/BAS, depression, anxiety, impulsivity, anger, and resilience. We used the PROCESS macro in SPSS to perform moderation and mediation analysis. Findings revealed that although a somewhat similar mediation model was supported in both sexes, moderating effects of resilience only emerged in girls. The results showed a protective role of resilience differing between sexes. These results suggest that clinicians should consider sex in the way resilience works as a protective factor against Internet addiction and focus on mitigating the effects of vulnerability by enhancing resilience in female Internet addicts.

The increased prevalence of Internet Gaming Disorder (IGD) and the inclusion of IGD in DSM-5 and ICD-11 emphasizes the importance of measuring and describing the IGD symptoms. We examined the psychometric properties of the Diagnostic Interview for Internet Addiction (DIA), a semi-structured diagnostic interview tool for IGD, and verified the application of DIA in clinical practice for Korean adolescents. The DIA is conducted in a manner that interviews both adolescents and their caregivers, and each item has a standardized representative question and various examples. It consists of 10 items based on the DSM-5 IGD diagnostic criteria, which is cognitive salience, withdrawal, tolerance, difficulty in regulating use, loss of interest in other activities, persistent use despite negative results, deception regarding Internet/games/SNS use, use of Internet/games/SNS to avoid negative feelings, interference with role performance, and craving. The study included 103 adolescents divided into three subgroups (mild risk, moderate risk, and addicted group) based on the total score of DIA. Demographic and clinical characteristics were compared among the DIA subgroups using the chi-square test and analysis of variance (ANOVA), and correlation analysis was used to examine the associations of IGD symptoms with clinical variables (e.g., impulsivity, aggression, depression, anxiety, self-esteem). The DIA total score was significantly correlated with Internet and smartphone addiction, depression, state anxiety, self-esteem, impulsivity, aggression, and stress. Furthermore, the moderate risk and addicted group showed significantly higher levels of Internet and smartphone addiction, anxiety, depression, impulsivity, aggression, stress, and lower self-esteem compared with the mild risk group. The Junior Temperament and Character Inventory (JTCI), which measures temperament and character traits, revealed that the mild risk group had higher levels of persistence and self-directedness than did the addicted group. Our findings confirmed the psychometric properties of DIA and the application of the DIA classifications in Korean adolescents.

This study investigated differences in the self-efficacy and clinical characteristics which were found relevant to addictive behaviors in young adults according to time spent gaming. To our knowledge, this is the first study to explore self-efficacy in casual gamers relative to patients with internet gaming disorder (IGD) and non-gamers. In total, 158 young adults participated in this study and were divided into three groups: excessive gamers, who were diagnosed with IGD based on the Diagnostic and Statistical Manual of Mental Disorder-fifth edition (DSM-5, n = 71); casual gamers, who played games regularly but did not meet the criteria for IGD (n = 37); and non-gamers/controls, who did not engage in gaming (n = 50). All participants completed self-administered questionnaires, including measures of self-efficacy and clinical features such as the Barratt Impulsiveness Scale, Beck Depression Inventory, Beck Anxiety Inventory, Behavioral Activation/Inhibition Systems, aggression, and psychosocial well-being. There were significant differences in the self-efficacy according to the extent of gaming (excessive gamers < casual gamers < non-gamers). In addition, aggression, impulsivity, depression, anxiety, level of stress, and behavioral inhibition system scores were significantly higher in excessive gamers than in casual gamers and non-gamers. These findings showed that individuals who spend more time playing games tend to have lower self-efficacy. Our study suggests that self-efficacy may protect against or constitute a risk of excessive gaming, particularly among casual gamers. It is necessary to pay attention to enhancing psychological well-being through self-efficacy to prevent addiction in young adult gamers.

This study aimed to examine the relationship of general cognitive function with gaming use, and to identify elements of intelligence predicting increased gaming use. In total, 160 young adults participated in this study. Two clinical groups (n = 97) were defined: excessive gaming users diagnosed with internet gaming disorder (IGD) (n = 64) and the high-risk users (n = 33). The control group (n = 63) was also divided into regular gamers (n = 14) and non-gamers (n = 49). Participants completed the Wechsler Adult Intelligence Scale-IV and self-reported questionnaires regarding IGD severity and gaming hours. The IGD group had significantly lower Full Scale Intelligence Quotient (FSIQ), Verbal Comprehension Index (VCI), and Processing Speed Index (PSI) scores, compared with regular gamers and non-gamers. The IGD group also exhibited lower Working Memory Index (WMI) scores, compared with non-gamers. The high-risk group demonstrated significantly lower PSI score, compared with non-gamers. Furthermore FSIQ, VCI, WMI, and PSI scores were significant predictors of gaming hours in the IGD group. For the high-risk group, FSIQ, WMI, and VCI scores were negatively associated with gaming hours. Our study demonstrates the need to address the importance of enhancing working memory and verbal ability, thus, preventing the development of gaming addiction among individuals at high-risk gamers.

Heart rate variability (HRV) can be used to represent the regulatory adaptive system and is a proxy for neurovisceral integration. Consistent with the view that, like other addictions, Internet gaming disorder (IGD) involves disrupted regulatory function, the present study hypothesized that IGD patients would show (a) decreased HRV, (b) ineffective functional neural connectivity, and (c) differential patterns of association between HRV and functional neural connectivity relative to healthy controls (HCs). The present study included 111 young adults (53 IGD patients and 58 age‐ and sex‐matched HCs) who underwent simultaneous recordings with an electrocardiogram and electroencephalogram during a resting state. Heart rate (HR), HRV, and functional neural connectivity were calculated using the graph theory approach. Compared with the HCs, the IGD patients exhibited elevated HR and decreased HRV based on the high frequency (HF), which reflects suppression of parasympathetic and/or vagal tone. The IGD patients also exhibited a heightened theta band characteristic path length (CPL) compared with HCs, indicating decreased efficacy of the functional network. Furthermore, IGD patients exhibited negative correlations between the standard deviation of the normal‐to‐normal interval index (SDNNi) and theta and delta CPL values, which were not observed in HCs. In conclusion, the present findings suggest that IGD patients might have maladaptive brain‐body integration features involving disruptions of the autonomic nervous system and brain function.