Introduction: TikTok use is increasing, especially among children and adolescents. However, the negative effects of TikTok use have not been sufficiently investigated. Aim: To examine the association between TikTok use and anxiety, depression, and sleepiness in adolescents. Methods: We conducted a web-based cross-sectional study in Greece. We employed a convenience sample of 219 adolescents in Greece. All participants had a TikTok account. We used the TikTok Addiction Scale (TTAS) to measure TikTok use and the Patient Health Questionnaire-4 (PHQ-4) to measure anxiety and depression. We constructed multivariable regression models, and we performed a stratified analysis according to gender. Results: The mean age was 18.5 years (standard deviation: 0.5, range: 18 to 19). In our sample, 81.3% were girls and 18.7% were boys. Mean daily TikTok usage and TTAS scores were statistically higher for girls than for boys. Our multivariable linear regression analysis was adjusted for age and showed that problematic TikTok use was associated with higher levels of anxiety and depression symptoms in both genders. In particular, we found a positive association between mood modification and anxiety score (beta = 0.404, p-value = 0.006). Moreover, we found a positive association between conflict and depression score (beta = 0.472, p-value < 0.001). Additionally, we found that the impact of TikTok on anxiety and depression was greater among boys than girls. We also found that problematic TikTok use was associated with increased sleepiness in both genders (mood modification: beta = 0.655, p-value < 0.001; conflict: beta = 0.674, p-value < 0.001). Conclusions: Our findings showed a positive association between TikTok use and anxiety, depression, and sleepiness. Early identification of problematic TikTok users is essential to promote their mental health and well-being. Healthcare professionals should be alert to recognize symptoms of problematic TikTok use.

TikTok use is increasing especially among children and adolescents. However, the negative effects of TikTok use have not been sufficiently investigated. Thus, the aim of our study was to examine the association between TikTok use and anxiety, depression, and sleepiness in adolescents. We conducted a web-based cross-sectional study in Greece. We employed a convenience sample of adolescents in Greece. We used the TikTok Addiction Scale (TTAS) to measure TikTok use, and the Patient Health Questionnaire-4 (PHQ-4) to measure anxiety and depression. We constructed multivariable regression models, and we performed stratified analysis according to gender. Mean daily TikTok usage and TTAS score was statistically higher for girls than boys. Our multivariable analysis showed that the problematic TikTok use was associated with higher levels of anxiety and depression symptoms in both genders. Additionally, we found that the impact of TikTok on anxiety and depression was higher among boys than girls. We found that problematic TikTok use was associated with increased sleepiness in both genders. Our findings showed the positive association between TikTok use and anxiety, depression, and sleepiness. Considering our study limitations and the limited number of studies on this field, future studies are necessary to produce more valid results.