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Author Gooley, J.J.; Rajaratnam, S.M.W.; Brainard, G.C.; Kronauer, R.E.; Czeisler, C.A.; Lockley, S.W. url  doi
openurl 
  Title Spectral responses of the human circadian system depend on the irradiance and duration of exposure to light Type Journal Article
  Year 2010 Publication Science Translational Medicine Abbreviated Journal Sci Transl Med  
  Volume 2 Issue 31 Pages 31ra33  
  Keywords Adolescent; Adult; Circadian Rhythm/physiology/*radiation effects; Dose-Response Relationship, Radiation; Humans; Light; Melatonin/secretion; Photoperiod; Phototherapy; Retina/physiology/radiation effects; Retinal Cone Photoreceptor Cells/physiology/radiation effects; Retinal Ganglion Cells/physiology/radiation effects; Rod Opsins/physiology; Young Adult; blue light; light at night; melatonin; melanopsin; light therapy  
  Abstract In humans, modulation of circadian rhythms by light is thought to be mediated primarily by melanopsin-containing retinal ganglion cells, not rods or cones. Melanopsin cells are intrinsically blue light-sensitive but also receive input from visual photoreceptors. We therefore tested in humans whether cone photoreceptors contribute to the regulation of circadian and neuroendocrine light responses. Dose-response curves for melatonin suppression and circadian phase resetting were constructed in subjects exposed to blue (460 nm) or green (555 nm) light near the onset of nocturnal melatonin secretion. At the beginning of the intervention, 555-nm light was equally effective as 460-nm light at suppressing melatonin, suggesting a significant contribution from the three-cone visual system (lambda(max) = 555 nm). During the light exposure, however, the spectral sensitivity to 555-nm light decayed exponentially relative to 460-nm light. For phase-resetting responses, the effects of exposure to low-irradiance 555-nm light were too large relative to 460-nm light to be explained solely by the activation of melanopsin. Our findings suggest that cone photoreceptors contribute substantially to nonvisual responses at the beginning of a light exposure and at low irradiances, whereas melanopsin appears to be the primary circadian photopigment in response to long-duration light exposure and at high irradiances. These results suggest that light therapy for sleep disorders and other indications might be optimized by stimulating both photoreceptor systems.  
  Address Division of Sleep Medicine, Department of Medicine, Brigham and Women's Hospital, Boston, MA 02115, USA  
  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 1946-6234 ISBN Medium  
  Area Expedition Conference  
  Notes PMID:20463367 Approved no  
  Call Number IDA @ john @ Serial 294  
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Author Meng, Y.; He, Z.; Yin, J.; Zhang, Y.; Zhang, T. url  doi
openurl 
  Title Quantitative calculation of human melatonin suppression induced by inappropriate light at night Type Journal Article
  Year 2011 Publication Medical & Biological Engineering & Computing Abbreviated Journal Med Biol Eng Comput  
  Volume 49 Issue 9 Pages 1083-1088  
  Keywords Algorithms; Circadian Rhythm/physiology/*radiation effects; Humans; *Lighting; Melatonin/*secretion; *Models, Biological; Retinal Cone Photoreceptor Cells/physiology/radiation effects; Retinal Ganglion Cells/physiology/radiation effects; Retinal Rod Photoreceptor Cells/physiology/radiation effects  
  Abstract Melatonin (C(1)(3)H(1)(6)N(2)O(2)) has a wide range of functions in the body. When is inappropriately exposed to light at night, human circadian rhythm will be interfered and then melatonin secretion will become abnormal. For nearly three decades great progresses have been achieved in analytic action spectra and melatonin suppression by various light conditions. However, so far few articles focused on the quantitative calculation of melatonin suppression induced by light. In this article, an algorithm is established, in which all the contributions of rods, cones, and intrinsically photosensitive retinal ganglion cells are considered. Calculation results accords with the experimental data in references very well, which indicate the validity of this algorithm. This algorithm can also interpret the rule of melatonin suppression varying with light correlated color temperature very well.  
  Address Photonics Research Center, School of Physics, Nankai University, Tianjin 300071, China  
  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 0140-0118 ISBN Medium  
  Area Expedition Conference  
  Notes PMID:21717231 Approved no  
  Call Number IDA @ john @ Serial 236  
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