BACKGROUND: This scoping review's aim is to provide a comprehensive overview of ecological momentary assessment (EMA)- based research on emotional labor (EL) as emotion regulation (ER). This includes an examination of the theoretical foundation this research builds on, how the hypothesized relationships are investigated using EMA methods as well as the studies' findings themselves. We built on the work of Grandey and Melloy (J Occup Health Psychol 22:407-22, 2004), who broadly distinguished between the two regulatory strategies of deep acting (DA) and surface acting (SA), embedded in a hierarchical model of emotional labor, as a guiding theory for structuring this review.

METHODS: To be included, studies had to use EMA to measure SA or DA, with no restrictions regarding population and date of publication. The electronic databases CINAHL, PsycArticles, PsycINFO, PSYNDEX, Embase, PubMed, and Web of Science were searched. Studies were included if they met the above criteria and were written in English or German. Out of 237 publications, 12 were chosen for this review.

RESULTS: All studies were based on emotional labor theories, with Arlie Hochschild's theory being the most popular, followed by Alicia Grandey's emotional labor theory and its modifications (Grandey AA. Emotion Regulation in the Workplace: A New Way to Conceptualize Emotional Labor; Grandey AA. When "the show must go on": Surface acting and deep acting as determinants of emotional exhaustion and peer-rated service delivery. 2003). The methodological quality of the studies varied greatly. The results of the studies indicate that SA is influenced by negative events, trait SA, service innovation and certain emotions, while DA is influenced by positive events and emotional intelligence. Emotional labor benefits the organization, e.g., by improving customer conflict handling, but also causes harm by increasing employee withdrawal behavior. For the employee, emotional labor results in more harm than benefits.

CONCLUSIONS: The research area is still in its early stages and the findings are mostly consistent, but the small number of studies needs to be replicated to increase the reliability of the results. The lack of evidence for ertain hypotheses highlights the presence of unresolved relationships that require further exploration. We are only at the beginning of investigating emotional labor using ecological momentary assessment, and conducting more high-quality studies will significantly enhance our comprehension of emotional labor.