The Relationship between Thermal Comfort and Light Intensity with Sleep Quality and Eye Tiredness in Shift Work Nurses

Environmental conditions such as lighting and thermal comfort are influencing factors on sleep quality and visual tiredness. The purpose of this study was the determination of the relationship between thermal comfort and light intensity with the sleep quality and eye fatigue in shift nurses. Method. This cross-sectional research was conducted on 82 shift-work personnel of 18 nursing workstations in Isfahan Al-Zahra Hospital, Iran, in 2012. Heat stress monitoring (WBGT) and photometer (Hagner Model) were used for measuring the thermal conditions and illumination intensity, respectively. To measure the sleep quality, visual tiredness, and thermal comfort, Pittsburg sleep quality index, eye fatigue questionnaire, and thermal comfort questionnaire were used, respectively. The data were analyzed with descriptive statistics, Student's t-test, and Pearson correlation. Results. Correlation between thermal comfort which was perceived from the self-reporting of people with eye tiredness was ？0.38 ( ). Pearson correlation between thermal comfort and sleep quality showed a positive and direct relationship ( , ) but the correlation between thermal comfort, which was perceived from the self-reporting of shift nurses, and WBGT index was a weak relationship ( ). Conclusion. Based on the obtained findings, it can be concluded that a defect in environmental conditions such as thermal conditions and light intensity and also lack of appropriate managerial plan for night shift-work nurses are destructive and negative factors for the physical and mental health of this group of practitioners. 1. Introduction Nursing is a profession which, because of its stressful nature, is being faced with unforeseen situations, shifting, and organizational and personal factors, and these agents affected the mental and physical health of nurses. Different studies have reported that, in comparison with the mental and physical health of people of our country, the mental and physical health of this group of society is in a lower level [1]. Altered circadian rhythm of the autonomic regulation can have important implications on the psychological and medical problems related to shift work. For example, increase in job stress and deterioration in mood or cognitive performance were seen in shift workers [2, 3], which may be associated with altered autonomic function [4, 5]. Some studies have reported that interns working 12？h consecutive night shifts demonstrated a reduction in visual memory capacity over the night shift [6]. Other studies have reported that sleep-deprived residents demonstrated