Short (≤ 6 hr) and long (≥ 9 hr) sleep durations are both associated with risk factors for cardiovascular diseases and diabetes, depression, learning problems, accidents and excess mortality. However, little is known about factors associated with sleep duration in Korean adults. This study examined sleep patterns in Korean adults and identified factors associated with short and long sleep durations. This study analyzed cross-sectional data collected from 4,411 Korean adults aged 19 yr and older who participated in a community health survey conducted in Gwangju, Korea. Multinomial logistic regression analysis was used to identify associations between socio-demographic and health-related factors and short or long sleep durations. Of the population, 37.2% and 4.0% reported short and long sleep, respectively. Short sleep was associated with older age, lower levels of income, night or shift work, heavy smoking, and depression or anxiety; long sleep was associated with younger age, being divorced or widowed, heavy smoking, underweight, depression or anxiety, and poorer self-reported health. In conclusion, a relatively high prevalence of short sleep duration is identified in this population of Korean adults. Factors associated with short or long sleep may act as potential confounders of the relationship between sleep duration and health outcomes.