Objectives We aimed to characterize the results obtained from Korean medical examinations and questionnaires on the quality of sleep. Methods The quality of sleep was measured using the Pittsburgh sleep quality index in 400 subjects. Afterwards, heart rate variability (HRV) measurements were done, along with the analyses for tongue color, teeth marks, and tongue coating through the tongue diagnosis system. A questionnaire about body's heat, cold and sweating conditions, and the perceived stress scale (PSS) were performed. Finally, correlations between all these indicators and the sleep quality were analyzed.Results As the quality of sleep decreased, the sympathetic nervous system was stimulated. The subjects who had the blue-purple colored tongue experienced decreased quality of sleep. The quality of sleep was also deteriorated in the subjects who usually feel cold and hot easily, sweat a lot, and feel a lot of discomfort. According to the PSS questionnaire, the higher the stress level is, the lower was the quality of sleep. Conclusions We obtained meaningful results by comprehensively analyzing the sleep quality, HRV, tongue diagnosis, heat and cold conditions, sweating, and stress conditions. In particular, the sleep quality had a significant correlation with the rest of the indicators.