The purpose of this study was to determine what affects the sleep parameters of the frail elderly. The subjects were 60 elderly people (11 male, 49 female, mean age 83.9±7.5 yrs) in a long-term care hospital. Subjects' sleep-wake patterns were monitored and recorded in a 59-days sleep log by nurses and/or care workers. The personal care problems chosen for this study were derived from Resident Assessment Protocols(RAPs) and their relationship was analyzed.The results revealed that the factors of 'Mood state' and 'Delirium' were signicantly related to the sleep parameters. Both the total sleep time and the longest uninterrupted sleep time during nighttime of the subjects without the problem of 'Mood state' were longer than those of the subjects with the problem (total sleep time: p<0.01, the longest uninterrupted sleep time during nighttime: p<0.05). Daytime sleep of the subjects without the problem of 'Delirium' was shorter than that of the subjects with the problem (p<0.05).It was suggested that some cares based on these results may improve the sleep-wake patterns in the frail elderly.