Abstract Background Sleep constitutes a fundamental biological necessity, occupying approximately one-third of our lifespan. Consequently, the field of sleep research has experienced an increase in interest, prompted by the recognition of insufficient sleep as a significant public health challenge. As the majority of existing questionnaires in Slovenia have yet to undergo official translation and validation processes, the aim of our study was to conduct content validation of a questionnaire designed to assess the sleep quality among adolescents. Methods We developed a test battery for assessing the sleep quality of adolescents by combining a diverse array of questionnaires. We employed the Adolescent Sleep-Wake Scale, Pediatric Daytime Sleepiness Scale, Epworth Sleepiness Scale for Children and Adolescents, and Children’s Morningness-Eveningness Scale. Following the development of the entire test battery, a process of back-translation from English to Slovene occurred, followed by cultural adaptation. Results The designed questionnaire underwent content validation by a panel of 10 experts drawn from diverse disciplines. Evaluation of questionnaire items followed a planned methodology tailored for the content validation of measurement instruments, focusing on content relevance, clarity, and classification into subscales or factors. Our analysis revealed that the individual questionnaires demonstrate content validity, supported by notably high indices of content validity. Conclusions Translated questionnaires demonstrate decent content validity, thus rendering them valid clinical and research tools for assessing sleep quality in adolescents in Slovenia. Key messages • Our research indicates the availability of content-valid tools for sleep research. • Further investigation is needed to determine the reliability, specificity, sensitivity, and appropriateness of the factorial structure of measures for the quality of sleep.