<p>The Pediatric Daytime Sleepiness Scale (PDSS) is a common tool for assessing daytime sleepiness in children and adolescents. Despite its widespread use, its internal consistency reliability across populations and cultures is still being assessed. This meta-analysis synthesizes data from multiple studies to assess the PDSS’s internal consistency. A comprehensive review of 18 databases was conducted to gather studies examining the reliability of PDSS using Cronbach’s alpha. A random-effects model was employed to calculate the overall Cronbach’s alpha, while the I² statistic and Tau² estimate assessed the consistency between studies. Subgroup analyses, meta-regression, and sensitivity analyses were performed to explore and verify the reasons for any observed differences. Additionally, funnel plot inspection, Egger’s regression, and trim-and-fill method were used to evaluate publication bias. The meta-analysis included nine studies with a total of 8064 participants (<i>k</i> = 9). The estimated pooled Cronbach’s alpha was 0.77 (95% CI 0.75 to 0.80), indicating high internal consistency. Significant heterogeneity was detected (I² = 87.88%, Tau² = 0.001, H² = 8.25). The prediction interval (0.69 to 0.86) suggested that most individual studies reported acceptable to excellent internal consistency. Subgroup and sensitivity analyses did not identify any unduly influential studies or significant moderators (age, sex). No evidence of publication bias was found using multiple assessment methods. The current meta-analysis confirms the high internal consistency reliability of the PDSS across varied study groups and cultures in non-clinical populations. While the findings support the international use of PDSS to assess daytime drowsiness in children and adolescents, validation in clinical populations remains necessary to establish its utility in diagnostic and treatment contexts. <i>Registration</i> Open Science Framework (OSF) <a href="https://doi.org/10.17605/OSF.IO/F7M3Z">https://doi.org/10.17605/OSF.IO/F7M3Z</a></p>