Impact of Sleep and Psychological Flexibility on Young Adults’ Physical and Mental Well-being

Young adults frequently report sleep issues, especially insomnia, delayed sleep phase, and sleep debt, with each of these contributing to distinct physical and mental well-being issues. This study explored the characteristics of sleep issues (Trisleep; sleep quantity, sleep quality, and sleep–wake rhythm) and psychological flexibility (Hexaflex; acceptance, cognitive defusion, self-as-context, commitment, values, and mindfulness) among young adults, analyzing their association with physical and mental well-being. All questionnaire data were collected online from 525 university students in Japan (men = 101, women = 414, unspecified = 10; M _age =19.96 ± 1.42 years). Their responses to questionnaires on sleep problems and psychological flexibility were analyzed via cluster analyses. Generalized linear models were used to compare the impacts of Trisleep and Hexaflex types on physical and mental well-being. In a cluster analysis, Four Trisleep types (good sleep, sleep–wake rhythm problems, sleep debt, and compound problems) and four Hexaflex types, differentiated by overall levels rather than distinct features (flexibility, medium flexibility, mild flexibility, and inflexibility) were identified. Trisleep types, especially compound sleep problems, were strongly associated with physical well-being. The interaction between Trisleep and Hexaflex types significantly predicted mental well-being, with Hexaflex having a greater impact. The findings underscore the importance of addressing both biological and psychological factors to enhance physical and mental well-being, with targeted interventions for sleep and psychological flexibility, potentially yielding effective outcomes for young adults.