Most of us prefer to kick back in sunshine and not under a fluorescent bulb, and it turns out there’s a scientific basis for that preference; the intensity of artificial lighting has been shown to have a range of effects not only on our mood, but also our ability to concentrate. A recent study conducted at the Korea Advanced Institute of Science and Technology (KAIST) in Daejeon, South Korea, examined the effects of different correlated color temperatures (CCTs) on the physiological alertness of schoolchildren, as manifested in academic performance and recess activities. CCT below 3500 K provides a warm, yellowish-white light, while a CCT over 5000 K casts cool, blueish-white light. The KAIST study, led by Kyungah Choi and Hyeon-Jeong Suk, examined the effects of 3500-, 5000- and 6000-K light, first in a simulated classroom and later in real-life classrooms. To test academic performance, fourth-grade students took timed arithmetic tests under LED lights tuned to the three CCT conditions in the lab. Choi and Suk found no significant variation between student performances under the three conditions. In a preliminary lab study using adults, they had found that 6500-K CCT light supported the highest level of physiological alertness, as measured by electrocardiogram-recording electrodes on the wrists and ankles, and 3500-K light was the most relaxing. Thinking length of exposure may explain the discrepancy in results, Suk and Choi studied two more groups of fourth-grade students, this time in real-life classrooms — one equipped with LED lights tuned to the three CCT conditions, and the other a control group using standard fluorescent lights. The students scored best on academic tests when they worked under the 6500 K lighting condition and performed best on recess activities under mellow 3500 K lighting. The results aligned with the preliminary study, but also with the century-old Yerkes-Dodson Law, which predicts a curvilinear relationship between mental arousal and performance, meaning people perform best at intermediate levels of stress. The duration of exposure to each lighting condition also seems to be key. Suk and Choi are honing in on the sweet-spot lighting for optimizing learning, and have even demonstrated a mobile-app-based dynamic lighting system with preset conditions of “easy,” “standard” and “intensive” for smart learning environments, believing even small changes could dramatically improve student learning. And here at Photonics Media headquarters, there’s a new entry for the company suggestion box.