The stability of the circadian rhythms, especially regarding their amplitude and phase relationship, is a major factor for health. Shift-work and working night shifts are known to be associated with a variety of health problems caused, at least partially, by the disturbance of biological rhythms. Seventeen undergraduate nursing students attending the morning program at Nursing School, and working night shifts as Nursing Technicians, were submitted to the morningness-eveningness questionnaire, sleep logs, and wrist temperature assessment, during two periods of 2 weeks (school term and vacation). The observed prominent ultradian periods and reduced amplitude of the daily rhythm of wrist temperature, in addition to the reduced sleep duration during the school term, reinforce the idea that the mixed routine contributes to the disruption of the expression of the circadian rhythms and may have detrimental effects on safety and performance at work.445737744