Purpose: This study examined the correlation of insomnia, sleep quality, depression, and circadian rhythm in nursing students. Methods: A total of 213 subjects completed a questionnaire consisting of their general characteristics, Insomnia Severity Index (ISI), Pittsburgh Sleep Quality Index (PSQI), Center for Epidemiologic Studies Depression (CES-D), and Composite Scale of Morningness (CSM). The collected data were analyzed by descriptive statistics, t-test, ANOVA, and Pearson's correlation coefficient using the SPSS 23.0 program. Results: The subjects' mean scores were ISI 7.18; PSQI 11.18; CES-D 16.00; and CSM 30.18. In insomnia, there were significant differences according to caffeine, perceived health status and major satisfaction. In sleep quality, there were significant differences according to perceived health status and major satisfaction. Significant differences in depression were observed according to gender, caffeine, subjective health status, major satisfaction, and circadian rhythm by drinking and exercise. A significant positive correlation was observed among ISI, PSQI, and CES-D. ISI and CES-D were negatively correlated. Conclusion: Tailored health care programs should be developed and applied to prevent and manage sleep-related and emotion-related problems in nursing students by considering the health status, major satisfaction, and gender.