The purpose of this study is to search for sleep quality and factors which are influenced on sleep among adolescents, adults and elderly Subjects were 108 adolescents, 85 adults and 114 elderly who live around Taegu city. The data were collected from August 10, 1998 to January 20, 1999. A self-rating questionnaire was used to collect data. Data were analysed in frequency, percentage, X^2 -test, means, standard deviation, t-test, ANOVA, and Scheffe test by SAS computer programme. The results of this study were as follows : The mean score on quality of sleep was 4.57 in adult, 5.79 in adolescents, and 6.71 in elderly. There were statistically significant in quality of sleep among three groups. The mean score of quality of sleep in adults was the highest compared to others. The subjective quality of sleep in elderly was poorer than adults. Quality of sleep in elderly was characterized by prolonged sleep latency, reduced sleep duration, lowered habitual sleep efficiency. Adolescents had the highest level of daytime dysfunction among the three groups. Factors which were influenced on sleep in daily life were investigated. Adolescents were disturbed by `nocturia(4.6%)`, `feeling too cold(4.6%)`, and `dreams(4.6%)`. Adults were disturbed by `nocturia(7.1%)`, `other reasons(5.9%)`, and `cough and loud snoring(2.4%)`. And the elderly were disturbed by `nocturia(75.5%)`, `other reasons(7.9%)`, `shortness of breath(4.4%)`, and `cough and loud snoring(4.4%). Nocturia was the common disturbing factor which was influenced on sleep in the elderly.