Development of the Japanese version of the work-life integration scale: Focusing on the work environment in Japan

In Japan, long working hours have become normalized, sometimes leading to serious societal issues such as death from overwork (karoshi) and suicide due to overwork (karojisatsu). Although the importance of work-life balance has been increasingly emphasized as a countermeasure, the diversification of work styles driven by remote work and technology has made it harder to clearly separate work and personal life. In response, this study focuses on the concept of "Work-Life Integration" (WLI) and aims to develop a tool for quantitatively assessing the actual state of WLI. Furthermore, it seeks to clarify the relationship between employment conditions and WLI. This study employed a longitudinal design, and collected data using self-reported measures. The WLI scale was translated into Japanese, and an online survey was conducted to evaluate the construct validity, convergent validity, discriminant validity, internal consistency, and test-retest reliability of the Japanese version (WLIS-J). Data from 704 employed individuals aged 20 years and older living in Japan were analyzed. Confirmatory factor analysis indicated that the original four-factor model did not fit the WLIS-J. An exploratory factor analysis revealed a new three-factor structure, comprising "Interference between Work and Life," "Work-Family Strain," and "Work-Family Enrichment." Convergent and discriminant validity were supported using five established scales measuring work-life enrichment, work-life conflict, job satisfaction, family satisfaction, and mental health. The Cronbach's alpha for the overall scale was  .85, with subscales ranging from  .80 to  .89, indicating adequate internal consistency. Intraclass correlation coefficients ranged from  .60 to  .75, confirming temporal stability. Furthermore, hierarchical multiple regression analyses, with WLI as the dependent variable, revealed that WLI was predicted by personal, work-related, and family-related factors. These findings suggest that the WLIS-J is a useful instrument for assessing work-life integration among Japanese workers, with long working hours in particular emerging as a significant predictor of WLI.