AIM: To describe the progression of vigilance and sleepiness over the shift and the coping strategies of nurses working 12-hr day or night shifts. BACKGROUND: The spread of 12-hr shift work in nursing raises the question of whether sufficient vigilance can be maintained to ensure quality of care. METHOD: 18 nurses working 12-hr shifts filled out a Karolinska Sleepiness Scale questionnaire and a Brief Psychomotor Vigilance Test, at the beginning of the shift and then every 3hr. Coping strategies and quality of care were assessed on self-administered questionnaires, filled out at 3hr, 6hr, 9hr and 12hr after the start of the shift. RESULTS: The present investigation did not show significantly excessive sleepiness or vigilance impairment or poor self-perception of quality of work during 12-hr nursing work shifts, although Psychomotor Vigilance Test results gradually deteriorated slightly over duty time (from start to end of shift). Certain coping strategies were preferred such as 'having a nap' later in the night shift. CONCLUSION: Attention needs to be paid to the health status of nurses working 12-hr shifts, with regular medical monitoring by the occupational health service. IMPLICATIONS FOR NURSING MANAGEMENT: Coping strategies to maintain sufficient vigilance to ensure quality of care should be facilitated.