The relationship between tea consumption and sleep quality: A bibliometric analysis

This study aims to analyzes the development of studies related to the relationship between tea consumption and sleep quality using a bibliometric approach based on 173 Scopus indexed documents from 2018 to 2024. Key keywords include "Sleep Quality", "Tea", "Herbal Tea", "Green Tea", and "Chamomile Tea". A bibliometric analysis with VOSviewer revealed the highest upward trend in publications in 2023 (32 documents), with the main contributions coming from the United States (13 publications, 522 citations), China (33 publications, 296 citations), and Japan (13 publications, 458 citations). Leading institutions include Ministry of Education of the People's Republic of China (5 publications) and University of Shizuoka (4 publications). Variations in research methodology were identified through the use of measurement tools such as the Pittsburgh Sleep Quality Index (PSQI), electroencephalography (EEG), and analysis of bioactive compounds (L-theanine and caffeine). The differences in that research were influenced by the type of tea (e.g. green tea vs. magnolia), the dose of consumption, and the characteristics of the participants (age, caffeine sensitivity). The results of this study suggest that tea has the potential to promote relaxation and reduce stress through neurochemical mechanisms, although the effects of caffeine need to be anticipated. The design implications of future research include the development of low-caffeine tea variants, the integration of psychometric methods (e.g., Stanford Sleepiness Scale), and a longitudinal approach to evaluating long-term impacts.