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Chronobiology/Circadian Disorders

October 1, 2013 (Tuesday)
Time of presentation: 19.00 to 20.00

Luciane Ruiz Carmona Ferreira – Brazil

Milva Maria Figueiredo De Martino (Brazil), Luciane Ruiz Carmona Ferreira (Brazil)

Introduction: Due to the increasing industrialization of society, the work in shifts is becoming increasingly common, as well as the development of night work, although with a pronounced negative effect on the workers sleep, performance and health.

Objective: to investigate the patterns of sleep-wake cycle and the circadian rhythmicity of peripheral body temperature, through measures taken at the wrist of nursing students who studies during the day and works on the night shift.

Methods: longitudinal descriptive study, with a quantitative approach, involving 27 adult subjects, nursing assistants and technicians who worked in the night shift and were students of undergraduate nursing of a private college in São Paulo State, during the daytime. The following instruments were used: Identification Form, Morningness Eveningness Questionnaire of Horne and Östberg, Sleep Diary, for 32 days, divided into school term and school vacations, and a thermistor (Thermochron iButton) on the non-dominant hand wrist to check the temperature of the wrist every 30 minutes.

Results: The adjustment of the temperature data of the wrist to a cosine curve, within a 24-hour period, a significant rhythmicity was verified in 35.3% of subjects in the school term and 93.7% of subjects in the vacation period, apart from the existence of different rhythms of the 24 hours such as 12 and 16 hours. There was a statistically significant difference in the time that the acrophase occurred, when comparing the school term on the days-off and on working days (p <0.0001), school vacation on the days-off and working days (p<0.0001) The sleep time during the school vacation was higher when the subjects didn’t sleep immediately after work. There was a significant difference when comparing the sleep time on the vacation period and days off (8:34) and school term and days off (7:24), p<0.0001, and also on vacation on working days (4:19), p=0.0496. Middle Phase of Sleep (MPS) there was a statistically significant difference between the school and vacation periods on working days and days off.

Conclusion: The presence of rhythms different than 24 hours, was observed especially during the school term, and the phase transfer of the wrist temperature, according to the period of work/study, with phase opposition on working days when compared to days off. The greatest spectral power was observed in the 24-hour rhythm, either during school term or vacation, confirming the hypothesis that the region of the wrist shows a well-defined and robust rhythmic expression. The findings reinforce the idea that the study favors the establishment of routine, but has little influence in displacing the body temperature, wich proved to be strongly influenced by the night shift work. Similar to the acrophase, the MPS showed great diversity in times of occurrence, but with a phase relation maintained between the rhythms on the different times of study.