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Author Wood, B.; Rea, M.S.; Plitnick, B.; Figueiro, M.G. url  doi
openurl 
  Title Light level and duration of exposure determine the impact of self-luminous tablets on melatonin suppression Type Journal Article
  Year 2013 Publication Applied Ergonomics Abbreviated Journal Appl Ergon  
  Volume 44 Issue 2 Pages 237-240  
  Keywords Adolescent; *Computers, Handheld; Female; Humans; Light/*adverse effects; Male; Melatonin/*biosynthesis; Photoperiod; Saliva/*metabolism; Sleep/radiation effects; Time Factors; Young Adult; melatonin  
  Abstract Exposure to light from self-luminous displays may be linked to increased risk for sleep disorders because these devices emit optical radiation at short wavelengths, close to the peak sensitivity of melatonin suppression. Thirteen participants experienced three experimental conditions in a within-subjects design to investigate the impact of self-luminous tablet displays on nocturnal melatonin suppression: 1) tablets-only set to the highest brightness, 2) tablets viewed through clear-lens goggles equipped with blue light-emitting diodes that provided 40 lux of 470-nm light at the cornea, and 3) tablets viewed through orange-tinted glasses (dark control; optical radiation <525 nm approximately 0). Melatonin suppressions after 1-h and 2-h exposures to tablets viewed with the blue light were significantly greater than zero. Suppression levels after 1-h exposure to the tablets-only were not statistically different than zero; however, this difference reached significance after 2 h. Based on these results, display manufacturers can determine how their products will affect melatonin levels and use model predictions to tune the spectral power distribution of self-luminous devices to increase or to decrease stimulation to the circadian system.  
  Address Lighting Research Center, Rensselaer Polytechnic Institute, 21 Union Street, Troy, NY 12180, USA. woodb5@rpi.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 (up) 0003-6870 ISBN Medium  
  Area Expedition Conference  
  Notes PMID:22850476 Approved no  
  Call Number IDA @ john @ Serial 136  
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Author Zukauskas, A.; Vaicekauskas, R.; Vitta, P. url  doi
openurl 
  Title Optimization of solid-state lamps for photobiologically friendly mesopic lighting Type Journal Article
  Year 2012 Publication Applied Optics Abbreviated Journal Appl Opt  
  Volume 51 Issue 35 Pages 8423-8432  
  Keywords Lighting Systems; Circadian Rhythm; Color; Equipment Design; Humans; Light; *Lighting; Melatonin/metabolism; Photobiology/*methods; Semiconductors; Time Factors; Vision, Ocular  
  Abstract The circadian and visual-performance-based mesopic systems of photometry were applied for the optimization of the spectral power distributions (SPDs) of the solid-state sources of light for low-illuminance lighting applications. At mesopic adaptation luminances typical of outdoor lighting (0.1-2 cd/m(2)), the optimal SPDs were obtained through the minimization of the mesopic circadian action factor, which is the ratio of the circadian efficacy of radiation to mesopic luminous efficacy of radiation. For correlated color temperatures below ~3000 K, the optimized dichromatic light-emitting diodes (LEDs) are shown to pose a lower circadian hazard than high-pressure sodium lamps and common warm white LEDs; also they are potentially more efficacious and have acceptable color rendition properties under mesopic conditions.  
  Address Institute of Applied Research, Vilnius University, Sauletekio al. 9-III, Vilnius LT-10222, Lithuania. arturas.zukauskas@ff.vu.lt  
  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 (up) 0003-6935 ISBN Medium  
  Area Expedition Conference  
  Notes PMID:23262538 Approved no  
  Call Number LoNNe @ christopher.kyba @ Serial 448  
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Author Kujanik, S.; Mikulecky, M. url  doi
openurl 
  Title Circadian and ultradian extrasystole rhythms in healthy individuals at elevated versus lowland altitudes Type Journal Article
  Year 2010 Publication International Journal of Biometeorology Abbreviated Journal Int J Biometeorol  
  Volume 54 Issue 5 Pages 531-538  
  Keywords Human Health; Acclimatization/physiology; Aged; *Altitude; Anoxia/etiology; Cardiac Complexes, Premature/*physiopathology; Circadian Rhythm/*physiology; Electrocardiography, Ambulatory; Heart Rate/*physiology; Humans; Male; Middle Aged; Reference Values; Time Factors  
  Abstract We defined chronobiologic norms for supraventricular and ventricular single extrasystoles (SV and VE, respectively) in healthy older males in lowland areas. The study was extended to higher altitudes, where hypobaric hypoxia was expected to increase extrasystole frequency, while perhaps not changing rhythmicity. In healthy men (lowland n = 37, altitude n = 22), aged 49-72 years, mean numbers of SVs and VEs were counted over a 24-h period. Cosinor regression was used to test the 24-h rhythm and its 2nd-10th harmonics. The resulting approximating function for either extrasystole type includes its point, 95% confidence interval of the mean, and 95% tolerance for single measurement estimates. Separate hourly differences (delta) between altitude and lowland (n = 59) were also analysed. Hourly means were significantly higher in the mountains versus lowland, by +0.8 beats/h on average for SVs, and by +0.9 beats/h for VEs. A relatively rich chronogram for VEs in mountains versus lowland exists. Delta VEs clearly display a 24-h component and its 2nd, 3rd, 4th and 7th harmonics. This results in significantly higher accumulation of VEs around 8.00 a.m., 11.00 a.m. and 3.00 p.m. in the mountains. The increase in extrasystole occurrence in the mountains is probably caused by higher hypobaric hypoxia and resulting sympathetic drive. Healthy men at elevated altitudes show circadian and several ultradian rhythms of single VEs dependent on the hypoxia level. This new methodological approach--evaluating the differences between two locations using delta values--promises to provide deeper insight into the occurrence of premature beats.  
  Address Dept of Physiology, Faculty of Medicine, Pavol Jozef Safarik University, Trieda SNP 1, 040 66 Kosice, Slovak Republic. stefan.kujanik@upjs.sk  
  Corporate Author Thesis  
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  Language English Summary Language Original Title  
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  ISSN (up) 0020-7128 ISBN Medium  
  Area Expedition Conference  
  Notes PMID:20195873 Approved no  
  Call Number LoNNe @ kagoburian @ Serial 774  
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Author Gooley, J.J.; Chamberlain, K.; Smith, K.A.; Khalsa, S.B.S.; Rajaratnam, S.M.W.; Van Reen, E.; Zeitzer, J.M.; Czeisler, C.A.; Lockley, S.W. url  doi
openurl 
  Title Exposure to room light before bedtime suppresses melatonin onset and shortens melatonin duration in humans Type Journal Article
  Year 2011 Publication The Journal of Clinical Endocrinology and Metabolism Abbreviated Journal J Clin Endocrinol Metab  
  Volume 96 Issue 3 Pages E463-72  
  Keywords Adolescent; Adult; Female; Humans; *Light; *Lighting; Male; Melatonin/*blood; Sleep/physiology; Time Factors; Young Adult  
  Abstract CONTEXT: Millions of individuals habitually expose themselves to room light in the hours before bedtime, yet the effects of this behavior on melatonin signaling are not well recognized. OBJECTIVE: We tested the hypothesis that exposure to room light in the late evening suppresses the onset of melatonin synthesis and shortens the duration of melatonin production. DESIGN: In a retrospective analysis, we compared daily melatonin profiles in individuals living in room light (<200 lux) vs. dim light (<3 lux). PATIENTS: Healthy volunteers (n = 116, 18-30 yr) were recruited from the general population to participate in one of two studies. SETTING: Participants lived in a General Clinical Research Center for at least five consecutive days. INTERVENTION: Individuals were exposed to room light or dim light in the 8 h preceding bedtime. OUTCOME MEASURES: Melatonin duration, onset and offset, suppression, and phase angle of entrainment were determined. RESULTS: Compared with dim light, exposure to room light before bedtime suppressed melatonin, resulting in a later melatonin onset in 99.0% of individuals and shortening melatonin duration by about 90 min. Also, exposure to room light during the usual hours of sleep suppressed melatonin by greater than 50% in most (85%) trials. CONCLUSIONS: These findings indicate that room light exerts a profound suppressive effect on melatonin levels and shortens the body's internal representation of night duration. Hence, chronically exposing oneself to electrical lighting in the late evening disrupts melatonin signaling and could therefore potentially impact sleep, thermoregulation, blood pressure, and glucose homeostasis.  
  Address Division of Sleep Medicine, Brigham and Women's Hospital and Harvard Medical School, 221 Longwood Avenue, Boston, Massachusetts 02115, USA. gmsjjg@nus.edu  
  Corporate Author Thesis  
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  Language English Summary Language Original Title  
  Series Editor Series Title Abbreviated Series Title  
  Series Volume Series Issue Edition  
  ISSN (up) 0021-972X ISBN Medium  
  Area Expedition Conference  
  Notes PMID:21193540; PMCID:PMC3047226 Approved no  
  Call Number IDA @ john @ Serial 139  
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Author Filipski, E.; Subramanian, P.; Carriere, J.; Guettier, C.; Barbason, H.; Levi, F. url  doi
openurl 
  Title Circadian disruption accelerates liver carcinogenesis in mice Type Journal Article
  Year 2009 Publication Mutation Research Abbreviated Journal Mutat Res  
  Volume 680 Issue 1-2 Pages 95-105  
  Keywords Human Health; Animals; Alanine Transaminase/blood; Animals; Aspartate Aminotransferases/blood; Bile Duct Neoplasms/chemically induced/pathology; Bile Ducts, Intrahepatic/drug effects/pathology; Body Weight/drug effects; Carcinogens/administration & dosage/*toxicity; Carcinoma, Hepatocellular/chemically induced/pathology; Cholangiocarcinoma/chemically induced/pathology; Circadian Rhythm/*drug effects; Diethylnitrosamine/administration & dosage/*toxicity; Dose-Response Relationship, Drug; Injections, Intraperitoneal; Liver/drug effects/pathology; Liver Neoplasms/blood/*chemically induced/pathology; Male; Mice; Neoplasms, Multiple Primary/chemically induced/pathology; Sarcoma/chemically induced/pathology; Time Factors  
  Abstract BACKGROUND: The circadian timing system rhythmically controls behavior, physiology, cellular proliferation and xenobiotic metabolism over the 24-h period. The suprachiasmatic nuclei in the hypothalamus coordinate the molecular clocks in most mammalian cells through an array of circadian physiological rhythms including rest-activity, body temperature, feeding patterns and hormonal secretions. As a result, shift work that involves circadian disruption is probably carcinogenic in humans. In experimental models, chronic jet-lag (CJL) suppresses rest-activity and body temperature rhythms and accelerates growth of two transplantable tumors in mice. CJL also suppresses or significantly alters the expression rhythms of clock genes in liver and tumors. Circadian clock disruption from CJL downregulates p53 and upregulates c-Myc, thus favoring cellular proliferation. Here, we investigate the role of CJL as a tumor promoter in mice exposed to the hepatic carcinogen, diethylnitrosamine (DEN). METHODS: In experiment 1 (Exp 1), the dose-dependent carcinogenicity of chronic intraperitoneal (i.p.) administration of DEN was explored in mice. In Exp 2, mice received DEN at 10 mg/kg/day (cumulative dose: 243 mg/kg), then were randomized to remain in a photoperiodic regimen where 12 h of light alternates with 12 h of darkness (LD 12:12) or to be submitted to CJL (8-h advance of light onset every 2 days). Rest-activity and body temperature were monitored. Serum liver enzymes were determined repeatedly. Mice were sacrificed and examined for neoplastic lesions at 10 months. RESULTS: In Exp 1, DEN produced liver cancers in all the mice receiving 10 mg/kg/day. In Exp 2, mice on CJL had increased mean plasma levels of aspartate aminotransferase and more liver tumors as compared to LD mice at approximately 10 months (p = 0.005 and 0.028, respectively). The mean diameter of the largest liver tumor was twice as large in CJL vs LD mice (8.5 vs 4.4 mm, p = 0.027). In LD, a single histologic tumor type per liver was observed. In CJL, up to four different types were associated in the same liver (hepatocellular- or cholangio-carcinomas, sarcomas or mixed tumors). DEN itself markedly disrupted the circadian rhythms in rest-activity and body temperature in all the mice. DEN-induced disruption was prolonged for >or= 3 months by CJL exposure. CONCLUSIONS: The association of circadian disruption with chronic DEN exposure suggests that circadian clocks actively control the mechanisms of liver carcinogenesis in mice. Persistent circadian coordination may further be critical for slowing down and/or reverting cancer development after carcinogen exposure.  
  Address INSERM, U776 Rythmes Biologiques et Cancers, Hopital Paul Brousse, Villejuif F-94807, France  
  Corporate Author Thesis  
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  Language English Summary Language Original Title  
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  Series Volume Series Issue Edition  
  ISSN (up) 0027-5107 ISBN Medium  
  Area Expedition Conference  
  Notes PMID:19833225 Approved no  
  Call Number LoNNe @ kagoburian @ Serial 747  
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