| Light exerts a wide range of non-visual biological effects on human apart from the visual effect.Light can regulate human circadian rhythms,the secretion of endogenous hormones,like melatonin and cortisol.Light also has influence on body’s physiological parameters,such as body temperature,blood pressure and heart rate.And even the human alertness,mood and cognition can be affected by different lighting conditions.Currently,the research about human non-visual biological effects mainly focus on establishing the spectrum response curve which based on melatonin suppression or pupil contraction,studying body’s physiological parameters under different lighting conditions.But most of these studies were conducted in the laboratory,not in the real workplaces.Besides,with the emergence of the new green light source LED,LED has gradually replaced the traditional incandescent and fluorescent lamp due to its advantages of energy-saving,environmental friendly,high efficiency and both flexible on spectrum and intensity.The study on non-visual biological effects based on LED lighting has become a new direction.Therefore,in this paper,a LED surgical lamp was designed.An experiment was conducted to investigate the alertness,mood and cognition of healthy participants in a simulated operating room(OR)in the hospital,and this LED surgical lamp was used as the light source.Firstly,the development of non-visual biological effects and LED lighting was reviewed.The principles of visual effect and non-visual effect were introduced,which included the three types of photoreceptors in human retina,visual and non-visual pathways between human eyes and brain.These knowledge are the theoretical basis of the non-visual biological effects.Secondly,a LED lighting system was designed to create different lighting conditions.According to the current surgical lamps in the hospital,a LED surgical lamp was designed,it consists of four panels,for with 12 blue LEDs,12 green LEDs and 12 amber LEDs.By the combination of these three color LEDs,the LED lamp is flexible on both spectrum and intensity.And the LED surgical lamp was measured and calibrated by PR-655.Finally,the LED surgical lamp was used as the light source,a within-subjects repeated-measured experiment was conducted in a simulated operating room to explore the participants,alertness,mood and cognition under different LED lighting conditions which varied from color temperature and luminance.There were three levels for luminance(3 000cd/m2,6000cd/m2,9000cd/m2)and three levels for color temperature(4000K,5000K,6500K),so there were 9 lighting conditions totally.The repeated-measures analysis of variance(r-ANOVA)and post hoc analysis were used to identify the main effects of different lighting conditions.The results showed that the luminance of LED surgical lighting had no significant effects on participants’ alertness,mood and cognition.But revealed that the color temperature of LED surgical lighting was the main effect of participants’ positive mood and cognition.The results also provided some guidance for the actual surgical lighting. |
