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Author (up) Higuchi, S.; Lee, S.-I.; Kozaki, T.; Harada, T.; Tanaka, I. url  doi
openurl 
  Title Late circadian phase in adults and children is correlated with use of high color temperature light at home at night Type Journal Article
  Year 2016 Publication Chronobiology International Abbreviated Journal Chronobiol Int  
  Volume 33 Issue 4 Pages 448-452  
  Keywords Children; circadian rhythm; light; melatonin  
  Abstract Light is the strongest synchronizer of human circadian rhythms, and exposure to residential light at night reportedly causes a delay of circadian rhythms. The present study was conducted to investigate the association between color temperature of light at home and circadian phase of salivary melatonin in adults and children. Twenty healthy children (mean age: 9.7 year) and 17 of their parents (mean age: 41.9 years) participated in the experiment. Circadian phase assessments were made with dim light melatonin onset (DLMO). There were large individual variations in DLMO both in adults and children. The average DLMO in adults and in children were 21:50 +/- 1:12 and 20:55 +/- 0:44, respectively. The average illuminance and color temperature of light at eye level were 139.6 +/- 82.7 lx and 3862.0 +/- 965.6 K, respectively. There were significant correlations between color temperature of light and DLMO in adults (r = 0.735, p < 0.01) and children (r = 0.479, p < 0.05), although no significant correlations were found between illuminance level and DLMO. The results suggest that high color temperature light at home might be a cause of the delay of circadian phase in adults and children.  
  Address a Department of Human Science, Faculty of Design , Kyushu University , Fukuoka , Japan  
  Corporate Author Thesis  
  Publisher Place of Publication Editor  
  Language English Summary Language Original Title  
  Series Editor Series Title Abbreviated Series Title  
  Series Volume Series Issue Edition  
  ISSN 0742-0528 ISBN Medium  
  Area Expedition Conference  
  Notes PMID:27010525 Approved no  
  Call Number LoNNe @ kyba @ Serial 1404  
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Author (up) Higuchi, S.; Nagafuchi, Y.; Lee, S.-I.; Harada, T. url  doi
openurl 
  Title Influence of Light at Night on Melatonin Suppression in Children Type Journal Article
  Year 2014 Publication The Journal of Clinical Endocrinology and Metabolism Abbreviated Journal J Clin Endocrinol Metab  
  Volume 99 Issue 9 Pages 3298-3303  
  Keywords melatonin; light at night; photobiology; children  
  Abstract Context: The sensitivity of melatonin to light suppression is expected to be higher in children since children have large pupils and pure crystal lenses. However, melatonin suppression by light in children remains unclear. Objective: We investigated whether light-induced melatonin suppression in children is larger than that in adults. Methods: Thirty-three healthy primary school children (mean age: 7.4 +/- 1.8 yr) and 29 healthy adults (mean age: 41.2 +/- 4.8 yr) participated in two experiments. In the first experiment, salivary melatonin concentrations in 13 children and 13 adults were measured at night under a dim light (< 30 lx) and moderately bright light (580 lx) in an experimental facility. Pupil diameters were also measured under dim light and bright light. In the second experiment, melatonin concentrations in 20 children and 16 adults were measured under dim light in the experimental facility and under room light at home (illuminance 140.0 +/- 82.7 lx). Results: In the experiment 1, the melatonin concentration was significantly decreased by exposure to moderately bright light in both adults and children. Melatonin suppression was significantly larger in children (88.2%, n=5) than in adults (46.3%, n=6) (p<0.01), although the data for some participants were excluded because melatonin concentrations had not yet risen. In the experiment 2, melatonin secretion was significantly suppressed by room light at home in children (n=15) (p<0.05) but not in adults (n=11). Conclusion: We found that the percentage of melatonin suppression by light in children was almost twice that in adults, suggesting that melatonin in children is more sensitive than that in adults to light at night.  
  Address Department of Human Science, Faculty of Design, Kyushu University, Fukuoka, Japan  
  Corporate Author Thesis  
  Publisher Place of Publication Editor  
  Language English Summary Language Original Title  
  Series Editor Series Title Abbreviated Series Title  
  Series Volume Series Issue Edition  
  ISSN 0021-972X ISBN Medium  
  Area Expedition Conference  
  Notes PMID:24840814 Approved no  
  Call Number IDA @ john @ Serial 300  
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