[Alternating shifts: mental fatigue in nurses].
The goal of the present study was to detect signs and symptoms of mental fatigue in nurses working in the hospital with shift schedule. The signs and symptoms of mental fatigue were measured by a subjective indicator, composed of a check list and two objective indicators called critical frequency of light fusion (Flicker) and Reaction Time to auditive stimulus (RTs). During fifteen consecutive days, morning, afternoon and night shifts of 12 nurses working in three different units of a university hospital were analyzed. The great rotation in work schedule, when in just one week a nurse can work up to three different shifts, is hazardous to the health, social, familiar and professional life of those nurses, who were not satisfied with the work schedule adopted by the institution and showed signs and symptoms of mental fatigue. The incidence of symptoms was greater for the night than for the morning shift which was greater than the afternoon shift and they frequently showed irritabilig and sleep disturbances. Indications of mental fatigue were detected by Flicker verification in the following order: morning shift greater than night shift which was greater than afternoon shift. On the other hand, using RTs the following indices of fatigue were detected: greater in the evening shift than morning shift which was greater than the afternoon shift.