ABSTRACT
<b>Objective</b>: In the present study, we conducted a clinical study to investigate the effect of newly developed LED lighting on improving sleep quality and living comfort in an indoor environment.<br> <b>Design</b>: Twelve healthy male subjects, whose Pittsburgh Sleep Quality Index (PSQI) scores were ≥5 participated in a randomized crossover trial. On the first day, as a sleep evaluation period, subjects rested from 21:00 to 22:00 under the newly developed lighting or ordinary lighting, went to bed at 22:00 and got up at 7:00. On the second day, as an evaluation period of daytime use, they performed a mental load for 4 hours under each lighting condition. We evaluated the quality of sleep by SLEEP SCAN and the St. Mary’s Hospital sleep questionnaire, and daytime performance by Uchida-Kraepelin psychodiagnostic test and advanced trail-making test (ATMT).<br> <b>Result</b>: The newly developed lighting improved the quality of sleep and increased comfortable feelings among participants; moreover, in daytime use, the environment did not induce impaired performance in spite of lower illumination.<br> <b>Conclusion</b>: This newly developed LED lighting produces suitable illumination and color temperature before sleeping and is useful for improving the living comfort in an indoor environment.<br>