Introduction: In many workplaces, there is exposure to heat and light simultaneously. This study investigated the combined effect of heat and lighting on some cognitive performances, i.e. reaction time. Methods:The present semi-experimental study was conducted in 2015 on 33 healthy students (16 girls and 17 boys) with a mean age of 22.1 in a thermal stress chamber. The reaction time parameter was measured by a reaction time measurement device, after exposure to different heat surfaces (dry temperatures of 22°C and 37°C) and lighting surfaces (200, 500 and 1500 lux). Data were analyzed using ANOVA test in SPSS 20. Results: The results showed that the average simple, diagnostic, two-color selective, twosound selective reaction times and reaction time error increased after combined exposure to heat and lighting, which showed a significant difference (P > 0.05). The maximum score of reaction time belonged to 37°C and 1500 lux, the minimum score of reaction time belonged to 22°C and 1500 lux. Conclusions:The results of this study showed that increasing the levels of heat and lighting by increasing the reaction time and reaction time error of people can decrease the cognitive performance. Therefore, workplaces must be optimized and attended in terms of heat and lighting.

Introduction: Few studies were conducted to determine the effects of lighting on cognitive performance. However, they could not reach a decisive conclusion. This study investigated cognitive performance of university students exposed to different levels of lighting under laboratory conditions. Methods: In this experimental study, 33 subjects (age range 19-26 years) performed cognitive tests. Participants were exposed to three levels of lighting (200, 500 and 1500lux) in laboratory conditions while performing CPT tests to investigate percentage of attention and reaction time machine that measures reaction time. Results: The results of this study showed that the maximum percentage of attention (99.75%) belonged to lighting of 1500 (lux) and the minimum percentage of attention was related to 500(lux) (99.36%). statistical analysis showed significant differences in percentage of attention in different levels of lighting (P=0.004). In addition, results of data analysis showed that increase in intensity of lighting can make a significant change in the average response time (P˂0.001), correct response (P=0.004), commission error (P=0.001) and omission error (P=0.017). With increasing the lighting intensity, reaction time has decreased. The reaction time showed significant differences at all levels of lighting (P˂0.001) Conclusion: According to the findings of this study, lighting causes a decrease in reaction time and increase in attention. Thus, the lighting should be taken into account while designing of job and tasks which need attention or reaction time.

Article Info Background: Work related musculoskeletal disorders (WRMSDs) have been described as one of the main health problems among healthcare workers. Adverse symptoms and disorders of the musculoskeletal system represent an important cause of occupational morbidity for employees around the world. Materials and Methods: The present study was performed with the aim to identify and characterize musculoskeletal symptoms in a sample including oral and maxillofacial surgeons In Tehran, Capital city of Iran. A cross-sectional identity self-reported Nordic Musculoskeletal Questionnaire (NMQ) was sent to 45 oral and maxillofacial surgeons. Study population completed the Standardized Nordic questionnaire. Results: Data were analyzed using descriptive statistics in the Statistical Package for the Social Science (SPSS) software. Of the study sample (n = 40), 63.0% and 37.0% of the participants were men and women, respectively. Musculoskeletal symptoms in the lower back with 56.8% were reported to be the most incident symptom, followed by the neck, upper back, and shoulders with a rate of 84.6%, 44.1%, and 37.4%, respectively. The most common symptoms were stiffness in the neck, pain in the lower back, numbness in the wrist/hand, weakness in the wrist/hand, and contusion in the shoulder as 84.0 %, 64.3%, 18.5%, 29.0%, and 42.0%, respectively. As the weight of most of the participants was in the normal range, body mass index (BMI) was not associated with musculoskeletal disorders (MSDs). Conclusions: This study showed a high incidence of self-reported musculoskeletal symptoms in some body regions among Iranian oral and maxillofacial surgeons. This indicated the need for developing occupational health programs for managing MSDs among surgeons.