<p>Young adults frequently report sleep issues, especially insomnia, delayed sleep phase, and sleep debt (Trisleep), with each of these contributing to distinct physical and mental well-being issues. Psychological flexibility (Hexaflex) has likewise been shown to relate to both physical and mental well-being. This study explored the Trisleep and Hexaflex among young adults, analyzing their association with physical and mental well-being. All questionnaire data were collected online from 525 university students in Japan (<i>M</i>_<i>age</i> = 19.96 ± 1.42 years). In a cluster analysis, four Trisleep types (good sleep, sleep–wake rhythm problems, sleep debt, and compound problems) and four Hexaflex types (flexibility, medium-flexibility, mild-flexibility, and inflexibility), differentiated by overall levels rather than distinct features were identified. Trisleep types (Deviance = 75.26, <i>p</i> &lt;  0.0001), especially compound sleep problems, strongly affected physical well-being (<i>t</i> = − 6.97, <i>p</i> &lt; 0.0001). The interaction between Trisleep and Hexaflex types significantly predicted mental well-being (Deviance = 20.81, <i>p</i> = 0.033). Across all sleep types, the Inflexibility type consistently had a stronger negative effect on mental well-being than the Flexibility type (<i>p</i>s &lt; 0.05). 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.</p>