We found that the percentage of melatonin suppression by light in children was almost twice that in adults, suggesting that melatonin is more sensitive to light in children than in adults at night.

Light‐induced melatonin suppression in children is reported to be more sensitive to white light at night than that in adults; however, it is unclear whether it depends on spectral distribution of lighting. In this study, we investigated the effects of different color temperatures of LED lighting on children's melatonin secretion during the night. Twenty‐two healthy children (8.9 ± 2.2 years old) and 20 adults (41.7 ± 4.4 years old) participated in this study. A between‐subjects design with four combinations, including two age groups (adults and children) and the two color temperature conditions (3000 K and 6200 K), was used. The experiment was conducted for two consecutive nights. On the first night, saliva samples were collected every hour under a dim light condition (<30 lx). On the second night, the participants were exposed to either color temperature condition. Melatonin suppression in children was greater than that in adults at both 3000 K and 6200 K condition. The 6200 K condition resulted in greater melatonin suppression than did the 3000 K condition in children (P < 0.05) but not in adults. Subjective sleepiness in children exposed to 6200 K light was significantly lower than that in children exposed to 3000 K light. In children, blue‐enriched LED lighting has a greater impact on melatonin suppression and it inhibits the increase in sleepiness during night. Light with a low color temperature is recommended at night, particularly for children's sleep and circadian rhythm.

No abstract

In recent years, health inequalities have become an important public health concern and the subject of both research and policy attention in Korea. Government reports, as well as many epidemiological studies, have provided evidence that a wide range of health outcomes and health-related behaviors are socioeconomically patterned, and that the magnitude of health inequalities is even increasing. However, except for the revised Health Plan 2010 targets for health equity, few government policies have explicitly addressed health inequalities. Although a number of economic and social policies may have had an impact on health inequalities, such impact has scarcely been evaluated. In this review, we describe the current status of research and policy on health inequalities in Korea. We also suggest future challenges of approaches and policies to reduce health inequalities and highlight the active and intensive engagement of many policy sectors and good evidence for interventions that will make meaningful reduction of health inequalities possible.