Use of minor tranquillizers and hypnotics and the association with shift work was examined in a sample of French nurses interviewed in 1980, 1985 and 1990. Permanent night schedule was related to a higher use of hypnotics/tranquillizers, the relation being significant in 1990. At each follow-up date, the use of drugs increased with sleep disorders, symptoms of psychological disorders reported by the nurses themselves, an impaired health and fatigue. Age was linked to the use of hypnotics/tranquillizers; the older the nurses were, the more likely they were to take the drugs. Using a logistic analysis, the following variables were significant: time schedules, self-assessment of health, fatigue, age and marital status. Time schedules involving night work, especially permanent night schedule, were related to a higher proportion of drug use. These findings confirmed the general patterns of psychotropic drug use (age, sleep disorders, physical health and marital status) among women and emphasized the relation between time schedules involving night work and the use of hypnotics/tranquillizers.