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Author Ruger, M.; Gordijn, M.C.M.; Beersma, D.G.M.; de Vries, B.; Daan, S. url  doi
openurl 
  Title Time-of-day-dependent effects of bright light exposure on human psychophysiology: comparison of daytime and nighttime exposure Type Journal Article
  Year 2006 Publication American Journal of Physiology. Regulatory, Integrative and Comparative Physiology Abbreviated Journal Am J Physiol Regul Integr Comp Physiol  
  Volume 290 Issue 5 Pages R1413-20  
  Keywords (up) Human Health; Adult; Body Temperature/*physiology; Circadian Rhythm/*physiology; Fatigue/*physiopathology; Heart Rate/*physiology; Humans; Hydrocortisone/*blood; *Light; Sleep Stages/*physiology  
  Abstract Bright light can influence human psychophysiology instantaneously by inducing endocrine (suppression of melatonin, increasing cortisol levels), other physiological changes (enhancement of core body temperature), and psychological changes (reduction of sleepiness, increase of alertness). Its broad range of action is reflected in the wide field of applications, ranging from optimizing a work environment to treating depressed patients. For optimally applying bright light and understanding its mechanism, it is crucial to know whether its effects depend on the time of day. In this paper, we report the effects of bright light given at two different times of day on psychological and physiological parameters. Twenty-four subjects participated in two experiments (n = 12 each). All subjects were nonsmoking, healthy young males (18-30 yr). In both experiments, subjects were exposed to either bright light (5,000 lux) or dim light <10 lux (control condition) either between 12:00 P.M. and 4:00 P.M. (experiment A) or between midnight and 4:00 A.M. (experiment B). Hourly measurements included salivary cortisol concentrations, electrocardiogram, sleepiness (Karolinska Sleepiness Scale), fatigue, and energy ratings (Visual Analog Scale). Core body temperature was measured continuously throughout the experiments. Bright light had a time-dependent effect on heart rate and core body temperature; i.e., bright light exposure at night, but not in daytime, increased heart rate and enhanced core body temperature. It had no significant effect at all on cortisol. The effect of bright light on the psychological variables was time independent, since nighttime and daytime bright light reduced sleepiness and fatigue significantly and similarly.  
  Address Department of Chronobiology, University of Groningen, The Netherlands. Melanie.Rueger@med.nyu.edu  
  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 0363-6119 ISBN Medium  
  Area Expedition Conference  
  Notes PMID:16373441 Approved no  
  Call Number LoNNe @ kagoburian @ Serial 801  
Permanent link to this record
 

 
Author Cajochen, C.; Jud, C.; Munch, M.; Kobialka, S.; Wirz-Justice, A.; Albrecht, U. url  doi
openurl 
  Title Evening exposure to blue light stimulates the expression of the clock gene PER2 in humans Type Journal Article
  Year 2006 Publication The European Journal of Neuroscience Abbreviated Journal Eur J Neurosci  
  Volume 23 Issue 4 Pages 1082-1086  
  Keywords (up) Human Health; Adult; Color; Darkness; Dose-Response Relationship, Radiation; Female; Gene Expression/*radiation effects; Humans; *Light; Male; Melatonin/metabolism; Mucous Membrane/metabolism/radiation effects; Nuclear Proteins/genetics/*metabolism; Period Circadian Proteins; Transcription Factors/genetics/*metabolism  
  Abstract We developed a non-invasive method to measure and quantify human circadian PER2 gene expression in oral mucosa samples and show that this gene oscillates in a circadian (= about a day) fashion. We also have the first evidence that induction of human PER2 expression is stimulated by exposing subjects to 2 h of light in the evening. This increase in PER2 expression was statistically significant in comparison to a non-light control condition only after light at 460 nm (blue) but not after light exposure at 550 nm (green). Our results indicate that the non-image-forming visual system is involved in human circadian gene expression. The demonstration of a functional circadian machinery in human buccal samples and its response to light opens the door for investigation of human circadian rhythms at the gene level and their associated disorders.  
  Address Centre for Chronobiology, Psychiatric University Clinics, University of Basel, CH-4025 Basel, Switzerland. christian.cajochen@unibas.ch  
  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 0953-816X ISBN Medium  
  Area Expedition Conference  
  Notes PMID:16519674 Approved no  
  Call Number LoNNe @ kagoburian @ Serial 727  
Permanent link to this record
 

 
Author Stevens, R.G. url  doi
openurl 
  Title Artificial lighting in the industrialized world: circadian disruption and breast cancer Type Journal Article
  Year 2006 Publication Cancer Causes & Control : CCC Abbreviated Journal Cancer Causes Control  
  Volume 17 Issue 4 Pages 501-507  
  Keywords (up) Human Health; Alcohol Drinking/adverse effects; Animals; Breast Neoplasms/*etiology; Chronobiology Disorders/*etiology/physiopathology; Circadian Rhythm; Developing Countries; Female; Humans; Lighting/*adverse effects; Melatonin/metabolism; Risk Factors; Suprachiasmatic Nucleus/physiopathology  
  Abstract Breast cancer risk is high in industrialized societies, and increases as developing countries become more Westernized. The reasons are poorly understood. One possibility is circadian disruption from aspects of modern life, in particular the increasing use of electric power to light the night, and provide a sun-free environment during the day inside buildings. Circadian disruption could lead to alterations in melatonin production and in changing the molecular time of the circadian clock in the suprachiasmatic nuclei (SCN). There is evidence in humans that the endogenous melatonin rhythm is stronger for persons in a bright-day environment than in a dim-day environment; and the light intensity necessary to suppress melatonin at night continues to decline as new experiments are done. Melatonin suppression can increase breast tumorigenesis in experimental animals, and altering the endogenous clock mechanism may have downstream effects on cell cycle regulatory genes pertinent to breast tissue development and susceptibility. Therefore, maintenance of a solar day-aligned circadian rhythm in endogenous melatonin and in clock gene expression by exposure to a bright day and a dark night, may be a worthy goal. However, exogenous administration of melatonin in an attempt to achieve this goal may have an untoward effect given that pharmacologic dosing with melatonin has been shown to phase shift humans depending on the time of day it's given. Exogenous melatonin may therefore contribute to circadian disruption rather than alleviate it.  
  Address University of Connecticut Health Center, Farmington, CT 06030-6325, USA. bugs@neuron.uchc.edu  
  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 0957-5243 ISBN Medium  
  Area Expedition Conference  
  Notes PMID:16596303 Approved no  
  Call Number LoNNe @ kagoburian @ Serial 818  
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Author Jasser, S.A.; Blask, D.E.; Brainard, G.C. url  doi
openurl 
  Title Light during darkness and cancer: relationships in circadian photoreception and tumor biology Type Journal Article
  Year 2006 Publication Cancer Causes & Control : CCC Abbreviated Journal Cancer Causes Control  
  Volume 17 Issue 4 Pages 515-523  
  Keywords (up) Human Health; Animals; *Circadian Rhythm; *Darkness; Humans; *Light; Light Signal Transduction; Melatonin/physiology/secretion; Neoplasms/etiology/pathology/*physiopathology; Suprachiasmatic Nucleus/physiology  
  Abstract The relationship between circadian phototransduction and circadian-regulated processes is poorly understood. Melatonin, commonly a circadian phase marker, may play a direct role in a myriad of physiologic processes. The circadian rhythm for pineal melatonin secretion is regulated by the hypothalamic suprachiasmatic nucleus (SCN). Its neural source of light input is a unique subset of intrinsically photosensitive retinal ganglion cells expressing melanopsin, the primary circadian photopigment in rodents and primates. Action spectra of melatonin suppression by light have shown that light in the 446-477 nm range, distinct from the visual system's peak sensitivity, is optimal for stimulating the human circadian system. Breast cancer is the oncological disease entity whose relationship to circadian rhythm fluctuations has perhaps been most extensively studied. Empirical data has increasingly supported the hypothesis that higher risk of breast cancer in industrialized countries is partly due to increased exposure to light at night. Studies of tumor biology implicate melatonin as a potential mediator of this effect. Yet, causality between lifestyle factors and circadian tumor biology remains elusive and likely reflects significant variability with physiologic context. Continued rigorous empirical inquiry into the physiology and clinical implications of these habitual, integrated aspects of life is highly warranted at this time.  
  Address Department of Neurology, Light Research Program, Thomas Jefferson University, 1025 Walnut Street, Suite 507, Philadelphia, PA 19107, USA. samar.jasser@jefferson.edu  
  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 0957-5243 ISBN Medium  
  Area Expedition Conference  
  Notes PMID:16596305 Approved no  
  Call Number LoNNe @ kagoburian @ Serial 766  
Permanent link to this record
 

 
Author Filipski, E.; Li, X.M.; Levi, F. url  doi
openurl 
  Title Disruption of circadian coordination and malignant growth Type Journal Article
  Year 2006 Publication Cancer Causes & Control : CCC Abbreviated Journal Cancer Causes Control  
  Volume 17 Issue 4 Pages 509-514  
  Keywords (up) Human Health; Animals; Biological Clocks; Body Temperature; Cell Cycle Proteins; Cell Line, Tumor; Chronobiology Disorders/*complications/physiopathology; Circadian Rhythm; Corticosterone/blood; DNA-Binding Proteins/metabolism; Jet Lag Syndrome/complications/physiopathology; Lymphocyte Count; Mice; Neoplasm Transplantation; Nuclear Proteins/metabolism; Nuclear Receptor Subfamily 1, Group D, Member 1; Osteosarcoma/*pathology/physiopathology; Pancreatic Neoplasms/*pathology/physiopathology; Period Circadian Proteins; Receptors, Cytoplasmic and Nuclear/metabolism; Suprachiasmatic Nucleus/physiopathology; Transcription Factors/metabolism  
  Abstract Altered circadian rhythms predicted for poor survival in patients with metastatic colorectal or breast cancer. An increased incidence of cancers has been reported in flying attendants and in women working predominantly at night. To explore the contribution of circadian structure to tumor growth we ablated the 24-h rest-activity cycle and markedly altered the rhythms in body temperature, serum corticosterone and lymphocyte count in mice by complete stereotaxic destruction of the suprachiasmatic nuclei (SCN) or by subjecting the mice to experimental chronic jet-lag. Such disruption of circadian coordination significantly accelerated malignant growth in two transplantable tumor models, Glasgow osteosarcoma and Pancreatic adenocarcinoma. The mRNA expression of clock genes per2 and reverb-alpha in controls displayed significant circadian rhythms in the liver (Cosinor, p=0.006 and p=0.003, respectively) and in the tumor (p=0.04 and p<0.001, respectively). Both rhythms were suppressed in the liver and in the tumor of jet lagged mice. This functional disturbance of molecular clock resulted in down regulation of p53 and overexpression of c-Myc, two effects which may favor cancer growth. CONCLUSIONS: These results indicate that circadian system could play an important role in malignant growth control. This should be taken into consideration in cancer prevention and therapy.  
  Address INSERM E 354 Cancer Chronotherapeutics, Hopital Paul Brousse, Villejuif, France. filipski@vjf.inserm.fr  
  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 0957-5243 ISBN Medium  
  Area Expedition Conference  
  Notes PMID:16596304 Approved no  
  Call Number LoNNe @ kagoburian @ Serial 748  
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