Light is said to be closely related to health, but such findings have not been disseminated to or practiced by the public. This article gives brief descriptions of the current activities of the Research Committee for Housing for Maintaining and Enhancing Health of the Ministry of Land, Infrastructure, Transport and Tourism's Housing bureau as a background how we came to plan this issue, and also described the effects of the lighting environment on one's physiology, psychology, and behavior. It also introduces how this issue is organized.

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Evening-typed infants showed low quality of sleep, short-sleep hours and lower mental health like as depression and anger based on continuous epidemiological studies performed in 2003-2008. Such studies also suggested that, first, sun-light exposure within three to four hours after the bottom point (early in the morning) of body temperature can make circadian-rhythm phase advanced, second, sun-light exposure after breakfast also make the children shifted to morning-type due to promoting serotonin synthesis in pineal, and third, the lighting with low color temperature lights in the first-half of subjective-night (evening) can make it sure that plasma-melatonin level in the night is kept high and circadian phase is in advance.

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Various studies show that light and the rhythms of a living body are closely related, and it has been demonstrated that: 1) morning light promotes the sleep-wake rhythm and works to reset the 25-hour circadian rhythm, the rhythm by which human beings are physiologically controlled, to 24 hours; 2) evening light works to set back the sleep-wake rhythm, and if a person is exposed to strong illumination at night, he/she will face a higher risk of suffering from delayed sleep-phase syndrome; and 3) if one is exposed to a strong light during the daytime, the amplitudes of the sleep-wake rhythm and the temperature rhythm will increase, thus leading to a refreshing daily life. It is important to take advantage of natural light and illumination effectively in order to get better sleep and to lead a healthy life.

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Melatonin is considered to be an important hormone for sound sleep and circadian regulation. It had firstly been found to be suppressed by high intensity light (2500lx) about 30 years ago then recent studies suggested it could be suppressed by household indoor lighting as well. In this report, a lower color temperature fluorescent lighting (2300K) than general products is introduced based on recently discovered action spectrum. It was proved to have less impact on melatonin secretion than 3000K and 5000K under same illuminance condition. Considering wavelength constitution will be more important in next generation lighting represented by LED.

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This article reports on the results of a survey conducted from the perspective of lifestyle and daytime and nighttime lighting environments that serve as a background when considering health. Tokyo area residents were surveyed via an internet questionnaire in December 2007. The results showed that residents are home in different patterns and thus have different lighting and dimming needs depending on age, presence of children, and other lifestyle parameters. The results implied that, going forward, the lighting environment will need to be controlled in a flexible manner depending on lifestyle.

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It has been 100 years since Edison invented the incandescent light bulb. Humans have created daytime in nighttime, and extended time for their activities. Even in the 21sth century, brighter and more beautiful illumination continues to evolve. However, many illumination designs of today are still under development and have many problems from the perspective of human physiology. This article focuses on Japan and Sweden, which are two countries with contrasting lighting environments, and introduces what those who are involved with illumination planning feel living in each country, our awareness of and engagement in lights and health in each country, discussions on future approaches to lighting.

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Lights have an impact on the health of many people; however, there is a light that only you yourself feel is healthy. Even though lights are one of many environmental factors, they influence one's emotions much more than air, heat, or sound. I conducted a questionnaire survey entitled, "what is a healthy light for you?" This article divides the results into various groups, and tries to discusses the forgettable relationship between light and health.

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I believe that this concept of "hikariiku" can show us a new approach to recent issues related to the global environment and energy saving. In other words, we should not just concentrate on energy saving techniques, but also carefully assess what kinds of light are essential to us, nurture high-quality lights while caring for the global environment, be nurtured by and come to terms with the lights-This is the lighting environment I believe is important.

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The First Lighting Symposium of China, Japan and Korea which was prepared through the cooperation of three illumination societies (the China Illuminating Engineering Society, the Illumination Engineering Institute of Japan, and the Korea Institute of Illuminating and Electrical Installation Engineers), was held in Beijing in October 2008. Three invited lectures the represented each country and forty-two prepublication papers (twelve oral presentations, and thirty poster presentations) were present. There were twenty-three participants from Japan, and twenty-one from Korea. Although there are still many improvements need be made, the symposium ended successfully, with many young participants and the enthusiasm of the host country. The second symposium is planned to be held in Sapporo in August 2009.

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I participated in the First Lighting Symposium of China, Japan and Korea in Beijing and had a valuable experience. I believe the symposium is very significant to the development of illumination not only in Japan, but also in Asia as a whole. I hope to contribute both to the success of the symposium in Japan next year and to the continued holding of the symposium in the future.

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"First Lighting Symposium of China, Japan and Korea" was held in Beijing in the People's Republic of China. The objectives of the symposium were to promote scientific and technical exchange in the field of lighting and to strengthen cooperation. And the themes of the symposium were energy saving and the global environment. There were six poster presentation from Japan, twelve from Korea, and one from the host country, China. This article gives a general outline of these poster session. The author hopes that it will serve as a reference material for graduate students and young researchers involved in lighting science and technology.

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