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Author Skeldon, A.C.; Phillips, A.J.K.; Dijk, D.-J.
Title The effects of self-selected light-dark cycles and social constraints on human sleep and circadian timing: a modeling approach Type Journal Article
Year 2017 Publication Scientific Reports Abbreviated Journal Sci Rep
Volume 7 Issue Pages 45158
Keywords (up) human health, lighting
Abstract Why do we go to sleep late and struggle to wake up on time? Historically, light-dark cycles were dictated by the solar day, but now humans can extend light exposure by switching on artificial lights. We use a mathematical model incorporating effects of light, circadian rhythmicity and sleep homeostasis to provide a quantitative theoretical framework to understand effects of modern patterns of light consumption on the human circadian system. The model shows that without artificial light humans wakeup at dawn. Artificial light delays circadian rhythmicity and preferred sleep timing and compromises synchronisation to the solar day when wake-times are not enforced. When wake-times are enforced by social constraints, such as work or school, artificial light induces a mismatch between sleep timing and circadian rhythmicity ('social jet-lag'). The model implies that developmental changes in sleep homeostasis and circadian amplitude make adolescents particularly sensitive to effects of light consumption. The model predicts that ameliorating social jet-lag is more effectively achieved by reducing evening light consumption than by delaying social constraints, particularly in individuals with slow circadian clocks or when imposed wake-times occur after sunrise. These theory-informed predictions may aid design of interventions to prevent and treat circadian rhythm-sleep disorders and social jet-lag.
Address University of Surrey, Surrey Sleep Research Centre, Guildford, GU2 7XP, UK
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 2045-2322 ISBN Medium
Area Expedition Conference
Notes PMID:28345624 Approved no
Call Number SU @ spitschan @ Serial 1638
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Author Price, L.L.A.; Lyachev, A.; Khazova, M.
Title Optical performance characterization of light-logging actigraphy dosimeters Type Journal Article
Year 2017 Publication Journal of the Optical Society of America. A, Optics, Image Science, and Vision Abbreviated Journal J Opt Soc Am A Opt Image Sci Vis
Volume 34 Issue 4 Pages 545-557
Keywords (up) Human Health, Lighting
Abstract There are several wearable products specially developed or marketed for studying sleep, circadian rhythms, and light levels. However, new recommendations relating to human physiological responses to light have changed what measurements researchers may demand. The performances of 11 light-logging dosimeters from eight manufacturers were compared. The directional and spectral sensitivities, linearity, dynamic range, and resolution were tested for seven models, and compared along with other published data. The sample mainly comprised light-logging actigraphy dosimeters wearable as badges, in accordance with measurement protocols for larger-scale field studies. A proposed standard for optical performance assessments is set out.
Address
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 1084-7529 ISBN Medium
Area Expedition Conference
Notes PMID:28375324 Approved no
Call Number SU @ spitschan @ Serial 1649
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Author Lerchl, A.; Schindler, C.; Eichhorn, K.; Kley, F.; Erren, T.C.
Title Indirect blue light does not suppress nocturnal salivary melatonin in humans in an automobile setting Type Journal Article
Year 2009 Publication Journal of Pineal Research Abbreviated Journal J Pineal Res
Volume 47 Issue 2 Pages 143-146
Keywords (up) Human Health; Adolescent; Adult; *Automobiles; Circadian Rhythm/physiology; Humans; *Lighting; Male; Melatonin/metabolism/*secretion; Salivary Glands/*secretion; Statistics, Nonparametric
Abstract In 2007, the International Agency for Research on Cancer (IARC) classified shift work that involves circadian disruption as being probably carcinogenic to humans (Group 2A). In this context, light exposure during the night plays a key role because it can suppress nocturnal melatonin levels when exposures exceed a certain threshold. Blue light around 464 nm is most effective in suppressing melatonin because of the spectral sensitivity of melanopsin, a recently discovered photopigment in retinal ganglion cells; the axons of these cells project to the suprachiasmatic nucleus, a circadian master clock in the brain. Due to advances in light technologies, normal tungsten light bulbs are being replaced by light-emitting diodes which produce quasi-monochromatic or white light. The objective of this study was to assess whether the light-melanopsin-melatonin axis might be affected in automobiles at night which employ the new generation diodes. To this end, we have tested in an experimental automobile setting whether indirect blue light (lambda(max) = 465 nm) at an intensity of 0.22 or 1.25 lx can suppress salivary melatonin levels in 12 male volunteers (age range 17-27 years) who served as their own controls. Daytime levels were low (2.7 +/- 0.5 pg/mL), and night-time levels without light exposure were high (14.5 +/- 1.1 pg/mL), as expected. Low-intensity light exposures had no significant effect on melatonin levels (0.22 lx: 17.2 +/- 2.8 pg/mL; P > 0.05; 1.25 lx: 12.6 +/- 2.0 pg/mL; P > 0.05). It is concluded that indirect blue light exposures in automobiles up to 1.25 lx do not cause unintentional chronodisruption via melatonin suppression.
Address School of Engineering and Science, Jacobs University, D-28759 Bremen, Germany. a.lerchl@jacobs-university.de
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 0742-3098 ISBN Medium
Area Expedition Conference
Notes PMID:19555449 Approved no
Call Number LoNNe @ kagoburian @ Serial 777
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Author Wright, K.P.J.; McHill, A.W.; Birks, B.R.; Griffin, B.R.; Rusterholz, T.; Chinoy, E.D.
Title Entrainment of the human circadian clock to the natural light-dark cycle Type Journal Article
Year 2013 Publication Current Biology : CB Abbreviated Journal Curr Biol
Volume 23 Issue 16 Pages 1554-1558
Keywords (up) Human Health; Adult; Circadian Clocks/*radiation effects; Female; Humans; *Lighting; Male; *Photoperiod; *Sunlight; Young Adult; Circadian Rhythm
Abstract The electric light is one of the most important human inventions. Sleep and other daily rhythms in physiology and behavior, however, evolved in the natural light-dark cycle [1], and electrical lighting is thought to have disrupted these rhythms. Yet how much the age of electrical lighting has altered the human circadian clock is unknown. Here we show that electrical lighting and the constructed environment is associated with reduced exposure to sunlight during the day, increased light exposure after sunset, and a delayed timing of the circadian clock as compared to a summer natural 14 hr 40 min:9 hr 20 min light-dark cycle camping. Furthermore, we find that after exposure to only natural light, the internal circadian clock synchronizes to solar time such that the beginning of the internal biological night occurs at sunset and the end of the internal biological night occurs before wake time just after sunrise. In addition, we find that later chronotypes show larger circadian advances when exposed to only natural light, making the timing of their internal clocks in relation to the light-dark cycle more similar to earlier chronotypes. These findings have important implications for understanding how modern light exposure patterns contribute to late sleep schedules and may disrupt sleep and circadian clocks.
Address Sleep and Chronobiology Laboratory, Department of Integrative Physiology, University of Colorado Boulder, Boulder, CO 80309-0354, USA. kenneth.wright@colorado.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 0960-9822 ISBN Medium
Area Expedition Conference
Notes PMID:23910656; PMCID:PMC4020279 Approved no
Call Number LoNNe @ christopher.kyba @ Serial 505
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Author Bauer, S.E.; Wagner, S.E.; Burch, J.; Bayakly, R.; Vena, J.E.
Title A case-referent study: light at night and breast cancer risk in Georgia Type Journal Article
Year 2013 Publication International Journal of Health Geographics Abbreviated Journal Int J Health Geogr
Volume 12 Issue Pages 23
Keywords (up) Human Health; Aged; Aged, 80 and over; Breast Neoplasms/*diagnosis/*epidemiology; Case-Control Studies; Circadian Rhythm/*physiology; Female; Georgia/epidemiology; Humans; Lighting/*adverse effects; Lung Neoplasms/diagnosis/epidemiology; Middle Aged; Registries; Risk Factors
Abstract BACKGROUND: Literature has identified detrimental health effects from the indiscriminate use of artificial nighttime light. We examined the co-distribution of light at night (LAN) and breast cancer (BC) incidence in Georgia, with the goal to contribute to the accumulating evidence that exposure to LAN increases risk of BC. METHODS: Using Georgia Comprehensive Cancer Registry data (2000-2007), we conducted a case-referent study among 34,053 BC cases and 14,458 lung cancer referents. Individuals with lung cancer were used as referents to control for other cancer risk factors that may be associated with elevated LAN, such as air pollution, and since this cancer type was not previously associated with LAN or circadian rhythm disruption. DMSP-OLS Nighttime Light Time Series satellite images (1992-2007) were used to estimate LAN levels; low (0-20 watts per sterradian cm(2)), medium (21-41 watts per sterradian cm(2)), high (>41 watts per sterradian cm(2)). LAN levels were extracted for each year of exposure prior to case/referent diagnosis in ArcGIS. RESULTS: Odds ratios (OR) and 95% confidence intervals (CI) were estimated using logistic regression models controlling for individual-level year of diagnosis, race, age at diagnosis, tumor grade, stage; and population-level determinants including metropolitan statistical area (MSA) status, births per 1,000 women aged 15-50, percentage of female smokers, MSA population mobility, and percentage of population over 16 in the labor force. We found that overall BC incidence was associated with high LAN exposure (OR = 1.12, 95% CI [1.04, 1.20]). When stratified by race, LAN exposure was associated with increased BC risk among whites (OR = 1.13, 95% CI [1.05, 1.22]), but not among blacks (OR = 1.02, 95% CI [0.82, 1.28]). CONCLUSIONS: Our results suggest positive associations between LAN and BC incidence, especially among whites. The consistency of our findings with previous studies suggests that there could be fundamental biological links between exposure to artificial LAN and increased BC incidence, although additional research using exposure metrics at the individual level is required to confirm or refute these findings.
Address Department of Epidemiology and Biostatistics, College of Public Health, University of Georgia, Athens, GA, USA. secbauer@ufl.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 1476-072X ISBN Medium
Area Expedition Conference
Notes PMID:23594790; PMCID:PMC3651306 Approved no
Call Number LoNNe @ kagoburian @ Serial 718
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