The scope of this study was to evaluate the sleep/wake cycle in shift work nurses, as well as their sleep quality and chronotype. The sleep/wake cycle was evaluated by keeping a sleep diary for a total of 60 nurses with a mean age of 31.76 years. The Horne & Östberg Questionnaire (1976) for the chronotype and the Pittsburgh Sleep Quality Index (PSQI) for sleep quality were applied. The results revealed a predominance of indifferent chronotypes (65.0%), followed by moderately evening persons (18.3%), decidedly evening persons (8.3%), moderately morning persons (6.6%) and decidedly morning persons (1.8%). The sleep quality perception was analyzed by the visual analogical scale, showing a mean score of 5.85 points for nighttime sleep and 4.70 points for daytime sleep, which represented a statistically significant difference. The sleep/wake schedule was also statistically different when considering weekdays and weekends. The PSQI showed a mean of 7.0 points, characterizing poor sleep quality. The results showed poor sleep quality in shift work nurses, possibly due to the lack of sport and shift work habits.