BackgroundLoneliness, sleep quality, psychological resilience, and self-esteem are closely related to young adults’ everyday psychological adjustment. However, less is known about how sleep quality is associated with loneliness among higher vocational college students and whether this association depends on internal psychological resources. This study examined the association between sleep quality and loneliness and tested the mediating role of psychological resilience and the moderating role of self-esteem.MethodsA cross-sectional survey was conducted from May to December 2023 in three higher vocational colleges in Heilongjiang Province, China. A total of 4,000 questionnaires were distributed, and 3,782 valid responses were included in the final analysis. Sleep quality, psychological resilience, self-esteem, and loneliness were assessed using the Pittsburgh Sleep Quality Index, 10-item Connor-Davidson Resilience Scale, Rosenberg Self-Esteem Scale, and 20-item UCLA Loneliness Scale, respectively. Pearson correlation analysis, multiple linear regression analyses, bootstrap mediation analysis, and moderated mediation analysis were performed. Fully adjusted models controlled for age, sex, grade, residence, family economic status, parental marital status, dormitory relationship, classmate relationship, academic pressure, and physical activity frequency.ResultsAmong the 3,782 participants, the mean age was 19.35 years (SD = 1.31); 1,593 participants were male (42.1%) and 2,189 were female (57.9%). Sleep quality was positively correlated with loneliness and negatively correlated with psychological resilience and self-esteem. Psychological resilience and self-esteem were negatively correlated with loneliness. In the fully adjusted mediation model, poorer sleep quality was associated with higher loneliness (β = 0.556, p < 0.01) and lower psychological resilience (β = −0.491, p < 0.01). Psychological resilience partially mediated the association between sleep quality and loneliness, with an indirect effect of 0.701, accounting for 45.93% of the total effect. The interaction between psychological resilience and self-esteem was significant (β = 0.119, p < 0.01). Conditional indirect effects were strongest among students with low self-esteem and weakest among those with high self-esteem, and the index of moderated mediation was significant.ConclusionPoorer sleep quality was associated with higher loneliness among higher vocational college students, and this association was partly explained by lower psychological resilience. Self-esteem further buffered the psychological resilience–loneliness pathway. These findings suggest that combining sleep health education, resilience enhancement, and self-esteem support may provide useful directions for reducing loneliness among higher vocational college students.