Introduction Insufficient sleep duration in adolescents is key public health concerns in many societies. This study aims to assess the prevalence of insufficient sleep duration and the association between short sleep with daytime sleepiness, depressive symptoms, and anxiety among Thai adolescents. Methods Thai adolescents aged 11 -18 years completed a self-administered questionnaire including Phramongkutklao Hospital Sleep disorders center Questionnaire, Pittsburg Sleep Quality Index (PSQI), Epworth Sleepiness Scale (ESS), The Children depress Inventory (CDI) scale and Child Anxiety Related Emotional Disorder (SCARED). Results 232 adolescents with the mean age of 14.58 (range 11-18) years participated in this survey. The average total sleep time was 7.44 hours. The overall prevalence of insufficient sleep duration (sleep duration <8 hours) was 37.5% and the small difference was found between males (42.0%) and females (32.7%). Compared with those who had a sleep length of 8 hours and more, insufficient sleep duration group exhibited higher in BMI and less in Grade Point Average (GPA). Subjective sleep insufficiency among Thai adolescent also had higher percentage of subjects with ESS ≥10 (43.2% vs 21.3%, P <0.001), depressive symptoms (56.3% vs 39.3%, P 0.012) and anxiety (54.0% vs 38.6%, P 0.022) compare to those with adequate sleep duration. Conclusion High amount of Thai adolescents with poor sleep duration were observed in the study, consistency with prior surveys. Insufficiency sleep duration group had significantly increased daytime sleepiness, mood and anxiety problems among Thai adolescents. These findings emphasized the development of interventions to improve sleep duration in Thai adolescents and more sample size should be achieved in the future. Support None