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Author Chellappa, S.L.; Viola, A.U.; Schmidt, C.; Bachmann, V.; Gabel, V.; Maire, M.; Reichert, C.F.; Valomon, A.; Gotz, T.; Landolt, H.-P.; Cajochen, C.
Title Human melatonin and alerting response to blue-enriched light depend on a polymorphism in the clock gene PER3 Type Journal Article
Year 2012 Publication The Journal of Clinical Endocrinology and Metabolism Abbreviated Journal J Clin Endocrinol Metab
Volume 97 Issue 3 Pages E433-7
Keywords (up) Adult; Alleles; Cross-Over Studies; Female; Genotype; Homozygote; Humans; *Light; Male; Melatonin/*blood/genetics; *Minisatellite Repeats; Period Circadian Proteins/*genetics; *Polymorphism, Genetic; Questionnaires; Sleep/genetics; Wakefulness/*genetics
Abstract CONTEXT: Light exposure, particularly at the short-wavelength range, triggers several nonvisual responses in humans. However, the extent to which the melatonin-suppressing and alerting effect of light differs among individuals remains unknown. OBJECTIVE: Here we investigated whether blue-enriched polychromatic light impacts differentially on melatonin and subjective and objective alertness in healthy participants genotyped for the PERIOD3 (PER3) variable-number, tandem-repeat polymorphism. DESIGN, SETTING, AND PARTICIPANTS: Eighteen healthy young men homozygous for the PER3 polymorphism (PER3(5/5)and PER3(4/4)) underwent a balanced crossover design during the winter season, with light exposure to compact fluorescent lamps of 40 lux at 6500 K and at 2500 K during 2 h in the evening. RESULTS: In comparison to light at 2500 K, blue-enriched light at 6500 K induced a significant suppression of the evening rise in endogenous melatonin levels in PER3(5/5) individuals but not in PER3(4/4). Likewise, PER3(5/5) individuals exhibited a more pronounced alerting response to light at 6500 K than PER3(4/4) volunteers. Waking electroencephalographic activity in the theta range (5-7 Hz), a putative correlate of sleepiness, was drastically attenuated during light exposure at 6500 K in PER3(5/5) individuals as compared with PER3(4/4). CONCLUSIONS: We provide first evidence that humans homozygous for the PER3 5/5 allele are particularly sensitive to blue-enriched light, as indexed by the suppression of endogenous melatonin and waking theta activity. Light sensitivity in humans may be modulated by a clock gene polymorphism implicated in the sleep-wake regulation.
Address Centre for Chronobiology, Psychiatric Hospital of the University of Basel, Wilhelm Kleinstrasse 27, CH-4012 Basel, Switzerland
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:22188742 Approved no
Call Number IDA @ john @ Serial 301
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Author Figueiro, M.G.; Bierman, A.; Plitnick, B.; Rea, M.S.
Title Preliminary evidence that both blue and red light can induce alertness at night Type Journal Article
Year 2009 Publication BMC Neuroscience Abbreviated Journal BMC Neurosci
Volume 10 Issue Pages 105
Keywords (up) Adult; Alpha Rhythm; Analysis of Variance; Beta Rhythm; Circadian Rhythm/*physiology; Cornea/physiology; Dose-Response Relationship, Radiation; Electrocardiography; Female; Humans; *Light; Male; Melatonin/secretion; Middle Aged; *Photic Stimulation; Psychomotor Performance; Radioimmunoassay; Salivary Glands/secretion; Wakefulness/*physiology; physiology of vision; blue light; red light
Abstract BACKGROUND: A variety of studies have demonstrated that retinal light exposure can increase alertness at night. It is now well accepted that the circadian system is maximally sensitive to short-wavelength (blue) light and is quite insensitive to long-wavelength (red) light. Retinal exposures to blue light at night have been recently shown to impact alertness, implicating participation by the circadian system. The present experiment was conducted to look at the impact of both blue and red light at two different levels on nocturnal alertness. Visually effective but moderate levels of red light are ineffective for stimulating the circadian system. If it were shown that a moderate level of red light impacts alertness, it would have had to occur via a pathway other than through the circadian system. METHODS: Fourteen subjects participated in a within-subject two-night study, where each participant was exposed to four experimental lighting conditions. Each night each subject was presented a high (40 lx at the cornea) and a low (10 lx at the cornea) diffuse light exposure condition of the same spectrum (blue, lambda(max) = 470 nm, or red, lambda(max) = 630 nm). The presentation order of the light levels was counterbalanced across sessions for a given subject; light spectra were counterbalanced across subjects within sessions. Prior to each lighting condition, subjects remained in the dark (< 1 lx at the cornea) for 60 minutes. Electroencephalogram (EEG) measurements, electrocardiogram (ECG), psychomotor vigilance tests (PVT), self-reports of sleepiness, and saliva samples for melatonin assays were collected at the end of each dark and light periods. RESULTS: Exposures to red and to blue light resulted in increased beta and reduced alpha power relative to preceding dark conditions. Exposures to high, but not low, levels of red and of blue light significantly increased heart rate relative to the dark condition. Performance and sleepiness ratings were not strongly affected by the lighting conditions. Only the higher level of blue light resulted in a reduction in melatonin levels relative to the other lighting conditions. CONCLUSION: These results support previous findings that alertness may be mediated by the circadian system, but it does not seem to be the only light-sensitive pathway that can affect alertness at night.
Address Lighting Research Center, Rensselaer Polytechnic Institute, Troy, NY, USA. figuem@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 1471-2202 ISBN Medium
Area Expedition Conference
Notes PMID:19712442; PMCID:PMC2744917 Approved no
Call Number IDA @ john @ Serial 285
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Author Kloog, I.; Stevens, R.G.; Haim, A.; Portnov, B.A.
Title Nighttime light level co-distributes with breast cancer incidence worldwide Type Journal Article
Year 2010 Publication Cancer Causes & Control : CCC Abbreviated Journal Cancer Causes Control
Volume 21 Issue 12 Pages 2059-2068
Keywords (up) Adult; Birth Rate; Breast Neoplasms/*epidemiology/etiology; Carcinoma/*epidemiology/etiology; Circadian Rhythm/*physiology; Cohort Studies; Electricity; Female; Humans; Incidence; *Light/adverse effects; Lighting; Photoperiod; Registries; Urban Population/statistics & numerical data; World Health; oncogenesis
Abstract Breast cancer incidence varies widely among countries of the world for largely unknown reasons. We investigated whether country-level light at night (LAN) is associated with incidence. We compared incidence rates of five common cancers in women (breast, lung, colorectal, larynx, and liver), observed in 164 countries of the world from the GLOBOCAN database, with population-weighted country-level LAN, and with several developmental and environmental indicators, including fertility rate, per capita income, percent of urban population, and electricity consumption. Two types of regression models were used in the analysis: Ordinary Least Squares and Spatial Errors. We found a significant positive association between population LAN level and incidence rates of breast cancer. There was no such an association between LAN level and colorectal, larynx, liver, and lung cancers. A sensitivity test, holding other variables at their average values, yielded a 30-50% higher risk of breast cancer in the highest LAN exposed countries compared to the lowest LAN exposed countries. The possibility that under-reporting from the registries in the low-resource, and also low-LAN, countries created a spurious association was evaluated in several ways and shown not to account for the results. These findings provide coherence of the previously reported case-control and cohort studies with the co-distribution of LAN and breast cancer in entire populations.
Address Department of Natural Resources & Environmental Management, University of Haifa, 31905 Mount Carmel, Haifa, Israel
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:20680434 Approved no
Call Number IDA @ john @ Serial 160
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Author Peplonska, B.; Bukowska, A.; Sobala, W.; Reszka, E.; Gromadzinska, J.; Wasowicz, W.; Lie, J.A.; Kjuus, H.; Ursin, G.
Title Rotating night shift work and mammographic density Type Journal Article
Year 2012 Publication Cancer Epidemiology, Biomarkers & Prevention : a Publication of the American Association for Cancer Research, Cosponsored by the American Society of Preventive Oncology Abbreviated Journal Cancer Epidemiol Biomarkers Prev
Volume 21 Issue 7 Pages 1028-1037
Keywords (up) Adult; Breast/*pathology; Breast Neoplasms/*etiology/*pathology; Circadian Rhythm/*physiology; Cross-Sectional Studies; Female; Humans; Melatonin/urine; Middle Aged; *Midwifery; *Nursing Staff; Questionnaires; Risk Factors; *Work Schedule Tolerance; oncogenesis
Abstract BACKGROUND: An increased risk of breast cancer has been observed in night shift workers. Exposure to artificial light at night and disruption of the endogenous circadian rhythm with suppression of the melatonin synthesis have been suggested mechanisms. We investigated the hypothesis that rotating night shift work is associated with mammographic density. METHODS: We conducted a cross-sectional study on the association between rotating night shift work characteristics, 6-sulfatoxymelatonin (MT6s) creatinine adjusted in a spot morning urine sample, and a computer-assisted measure of mammographic density in 640 nurses and midwives ages 40 to 60 years. The associations were evaluated using regression models adjusted for age, body mass index, menopausal status, age at menopause, age at menarche, smoking, and the calendar season of the year when mammography was conducted. RESULTS: The adjusted means of percentage of mammographic density and absolute density were slightly higher among women working rotating night shifts but not statistically significant [percentage of mammographic density = 23.6%, 95% confidence interval (CI), 21.9%-25.4% vs. 22.5%, 95% CI, 20.8%-24.3%; absolute density = 23.9 cm(2), 95% CI, 21.4-26.4 cm(2) vs. 21.8 cm(2), 95% CI, 19.4-24.3 cm(2) in rotating night shift and day shift nurses, respectively). There were no significant associations between the current or cumulative rotating night shift work exposure metrics and mammographic density. No association was observed between morning MT6s and mammographic density. CONCLUSIONS: The hypothesis on the link between rotating night shift work, melatonin synthesis disruption, and mammographic density is not supported by the results of the present study. IMPACT: It is unlikely that the development of breast cancer in nurses working rotating night shifts is mediated by an increase in mammographic density.
Address Department of Environmental Epidemiology, Nofer Institute of Occupational Medicine, Lodz, Poland. beatap@imp.lodz.pl
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 1055-9965 ISBN Medium
Area Expedition Conference
Notes PMID:22539602 Approved no
Call Number IDA @ john @ Serial 159
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Author Cajochen, C.; Frey, S.; Anders, D.; Spati, J.; Bues, M.; Pross, A.; Mager, R.; Wirz-Justice, A.; Stefani, O.
Title Evening exposure to a light-emitting diodes (LED)-backlit computer screen affects circadian physiology and cognitive performance Type Journal Article
Year 2011 Publication Journal of Applied Physiology (Bethesda, Md. : 1985) Abbreviated Journal J Appl Physiol (1985)
Volume 110 Issue 5 Pages 1432-1438
Keywords (up) Adult; Circadian Rhythm/*physiology/radiation effects; Cognition/*physiology/radiation effects; *Computer Terminals; Humans; Light; Lighting/*methods; Male; Photic Stimulation/*methods; Radiation Dosage; Semiconductors; *Task Performance and Analysis; Young Adult; blue light; sleep; circadian disruption
Abstract Many people spend an increasing amount of time in front of computer screens equipped with light-emitting diodes (LED) with a short wavelength (blue range). Thus we investigated the repercussions on melatonin (a marker of the circadian clock), alertness, and cognitive performance levels in 13 young male volunteers under controlled laboratory conditions in a balanced crossover design. A 5-h evening exposure to a white LED-backlit screen with more than twice as much 464 nm light emission {irradiance of 0,241 Watt/(steradian x m(2)) [W/(sr x m(2))], 2.1 x 10(13) photons/(cm(2) x s), in the wavelength range of 454 and 474 nm} than a white non-LED-backlit screen [irradiance of 0,099 W/(sr x m(2)), 0.7 x 10(13) photons/(cm(2) x s), in the wavelength range of 454 and 474 nm] elicited a significant suppression of the evening rise in endogenous melatonin and subjective as well as objective sleepiness, as indexed by a reduced incidence of slow eye movements and EEG low-frequency activity (1-7 Hz) in frontal brain regions. Concomitantly, sustained attention, as determined by the GO/NOGO task; working memory/attention, as assessed by “explicit timing”; and declarative memory performance in a word-learning paradigm were significantly enhanced in the LED-backlit screen compared with the non-LED condition. Screen quality and visual comfort were rated the same in both screen conditions, whereas the non-LED screen tended to be considered brighter. Our data indicate that the spectral profile of light emitted by computer screens impacts on circadian physiology, alertness, and cognitive performance levels. The challenge will be to design a computer screen with a spectral profile that can be individually programmed to add timed, essential light information to the circadian system in humans.
Address Centre for Chronobiology, Psychiatric Hospitals of the University of Basel, Basel, Switzerland. christian.cajochen@upkbs.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 0161-7567 ISBN Medium
Area Expedition Conference
Notes PMID:21415172 Approved no
Call Number IDA @ john @ Serial 293
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