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Author Cho, J.R.; Joo, E.Y.; Koo, D.L.; Hong, S.B. url  doi
openurl 
  Title Let there be no light: the effect of bedside light on sleep quality and background electroencephalographic rhythms Type Journal Article
  Year 2013 Publication Sleep Medicine Abbreviated Journal Sleep Med  
  Volume 14 Issue 12 Pages 1422-1425  
  Keywords Eeg; Light; Polysomnography; Sleep; Sleep spindle; Slow oscillation  
  Abstract OBJECTIVES: Artificial lighting has been beneficial to society, but unnecessary light exposure at night may cause various health problems. We aimed to investigate how whole-night bedside light can affect sleep quality and brain activity. PATIENTS AND METHODS: Ten healthy sleepers underwent two polysomnography (PSG) sessions, one with the lights off and one with the lights on. PSG variables related to sleep quality were extracted and compared between lights-off and lights-on sleep. Spectral analysis was performed to rapid eye movement (REM) sleep and non-REM (NREM) sleep epochs to reveal any light-induced differences in background brain rhythms. RESULTS: Lights-on sleep was associated with increased stage 1 sleep (N1), decreased slow-wave sleep (SWS), and increased arousal index. Spectral analysis revealed that theta power (4-8Hz) during REM sleep and slow oscillation (0.5-1Hz), delta (1-4Hz), and spindle (10-16Hz) power during NREM sleep were decreased in lights-on sleep conditions. CONCLUSIONS: Sleeping with the light on not only causes shallow sleep and frequent arousals but also has a persistent effect on brain oscillations, especially those implicated in sleep depth and stability. Our study demonstrates additional hazardous effect of light pollution on health.  
  Address Department of Neurology, Samsung Medical Center, Sungkyunkwan University School of Medicine, Seoul, Republic of Korea; Samsung Biomedical Research Institute, Seoul, Republic of Korea; Division of Computation and Neural Systems, California Institute of Technology, Pasadena, California, USA  
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  Language English Summary Language Original Title  
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  Series Volume Series Issue Edition  
  ISSN 1389-9457 ISBN Medium  
  Area Expedition Conference  
  Notes PMID:24210607 Approved no  
  Call Number IDA @ john @ Serial 141  
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Author Stokkan, K.-A.; Folkow, L.; Dukes, J.; Neveu, M.; Hogg, C.; Siefken, S.; Dakin, S.C.; Jeffery, G. url  doi
openurl 
  Title Shifting mirrors: adaptive changes in retinal reflections to winter darkness in Arctic reindeer Type Journal Article
  Year 2013 Publication Proceedings. Biological Sciences Abbreviated Journal Proc Biol Sci  
  Volume 280 Issue 1773 Pages 20132451  
  Keywords Animals; Skyglow  
  Abstract Arctic reindeer experience extreme changes in environmental light from continuous summer daylight to continuous winter darkness. Here, we show that they may have a unique mechanism to cope with winter darkness by changing the wavelength reflection from their tapetum lucidum (TL). In summer, it is golden with most light reflected back directly through the retina, whereas in winter it is deep blue with less light reflected out of the eye. The blue reflection in winter is associated with significantly increased retinal sensitivity compared with summer animals. The wavelength of reflection depends on TL collagen spacing, with reduced spacing resulting in shorter wavelengths, which we confirmed in summer and winter animals. Winter animals have significantly increased intra-ocular pressure, probably produced by permanent pupil dilation blocking ocular drainage. This may explain the collagen compression. The resulting shift to a blue reflection may scatter light through photoreceptors rather than directly reflecting it, resulting in elevated retinal sensitivity via increased photon capture. This is, to our knowledge, the first description of a retinal structural adaptation to seasonal changes in environmental light. Increased sensitivity occurs at the cost of reduced acuity, but may be an important adaptation in reindeer to detect moving predators in the dark Arctic winter.  
  Address Department of Arctic and Marine Biology, University of Tromso, , Tromso, Norway, Institute of Ophthalmology, University College London, , 11-43 Bath Street, London EC1V 9EL, UK, Moorfields Eye Hospital, , London, UK  
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  Language English Summary Language Original Title  
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  ISSN 0962-8452 ISBN Medium  
  Area Expedition Conference  
  Notes PMID:24174115; PMCID:PMC3826237 Approved no  
  Call Number LoNNe @ kyba @ Serial 1636  
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Author Hurley, S.; Nelson, D.O.; Garcia, E.; Gunier, R.; Hertz, A.; Reynolds, P. url  doi
openurl 
  Title A cross-sectional analysis of light at night, neighborhood sociodemographics and urinary 6-sulfatoxymelatonin concentrations: implications for the conduct of health studies Type Journal Article
  Year 2013 Publication International Journal of Health Geographics Abbreviated Journal Int J Health Geogr  
  Volume 12 Issue 1 Pages 39  
  Keywords circadian disruption; 6-sulftoxymelatonin; melatonin; aMT6s, DMSP; light at night  
  Abstract BACKGROUND: There is accumulating evidence that circadian disruption, mediated by alterations in melatonin levels, may play an etiologic role in a wide variety of diseases. The degree to which light-at-night (LAN) and other factors can alter melatonin levels is not well-documented. Our primary objective was to evaluate the degree to which estimates of outdoor environmental LAN predict 6-sulftoxymelatonin (aMT6s), the primary urinary metabolite of melatonin. We also evaluated other potential behavioral, sociodemographic, and anthropomorphic predictors of aMT6s. METHODS: Study participants consisted of 303 members of the California Teachers Study who provided a 24-hour urine specimen and completed a self-administered questionnaire in 2000. Urinary aMT6s was measured using the Buhlmann ELISA. Outdoor LAN levels were estimated from satellite imagery data obtained from the U.S. Defense Meteorological Satellite Program's (DMSP) Operational Linescan System and assigned to study participants' geocoded residential address. Information on other potential predictors of aMT6s was derived from self-administered surveys. Neighborhood socioeconomic status (SES) was based on U.S. Census block group data. RESULTS: Lower aMT6s levels were significantly associated with older age, shorter nights, and residential locations in lower SES neighborhoods. Outdoor sources of LAN estimated using low-dynamic range DMSP data had insufficient variability across urban neighborhoods to evaluate. While high-dynamic range DMSP offered much better variability, it was not significantly associated with urinary aMT6s. CONCLUSIONS: Future health studies should utilize the high-dynamic range DMSP data and should consider other potential sources of circadian disruption associated with living in lower SES neighborhoods.  
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  ISSN 1476-072X ISBN Medium  
  Area Expedition Conference  
  Notes PMID:24127816; PMCID:PMC3766028 Approved no  
  Call Number IDA @ john @ Serial 142  
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Author Prugh, L.R.; Golden, C.D. url  doi
openurl 
  Title Does moonlight increase predation risk? Meta-analysis reveals divergent responses of nocturnal mammals to lunar cycles Type Journal Article
  Year 2013 Publication The Journal of Animal Ecology Abbreviated Journal J Anim Ecol  
  Volume 83 Issue 2 Pages 504-514  
  Keywords foraging efficiency; giving-up density; illumination; indirect effects; lunar cycles; moonlight; nocturnality; phylogenetic meta-analysis; predation risk; risk-sensitive foraging  
  Abstract The risk of predation strongly affects mammalian population dynamics and community interactions. Bright moonlight is widely believed to increase predation risk for nocturnal mammals by increasing the ability of predators to detect prey, but the potential for moonlight to increase detection of predators and the foraging efficiency of prey has largely been ignored. Studies have reported highly variable responses to moonlight among species, calling into question the assumption that moonlight increases risk. Here, we conducted a quantitative meta-analysis examining the effects of moonlight on the activity of 59 nocturnal mammal species to test the assumption that moonlight increases predation risk. We examined patterns of lunarphilia and lunarphobia across species in relation to factors such as trophic level, habitat cover preference and visual acuity. Across all species included in the meta-analysis, moonlight suppressed activity. The magnitude of suppression was similar to the presence of a predator in experimental studies of foraging rodents (13.6% and 18.7% suppression, respectively). Contrary to the expectation that moonlight increases predation risk for all prey species, however, moonlight effects were not clearly related to trophic level and were better explained by phylogenetic relatedness, visual acuity and habitat cover. Moonlight increased the activity of prey species that use vision as their primary sensory system and suppressed the activity of species that primarily use other senses (e.g. olfaction, echolocation), and suppression was strongest in open habitat types. Strong taxonomic patterns underlay these relationships: moonlight tended to increase primate activity, whereas it tended to suppress the activity of rodents, lagomorphs, bats and carnivores. These results indicate that visual acuity and habitat cover jointly moderate the effect of moonlight on predation risk, whereas trophic position has little effect. While the net effect of moonlight appears to increase predation risk for most nocturnal mammals, our results highlight the importance of sensory systems and phylogenetic history in determining the level of risk.  
  Address Institute of Arctic Biology, University of Alaska Fairbanks, 311 Irving 1, Fairbanks, AK, 99775, USA  
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  ISSN 0021-8790 ISBN Medium  
  Area Expedition Conference  
  Notes PMID:24102189 Approved no  
  Call Number IDA @ john @ Serial 83  
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Author Dominoni, D.M.; Goymann, W.; Helm, B.; Partecke, J. url  doi
openurl 
  Title Urban-like night illumination reduces melatonin release in European blackbirds (Turdus merula): implications of city life for biological time-keeping of songbirds Type Journal Article
  Year 2013 Publication Frontiers in Zoology Abbreviated Journal Front Zool  
  Volume 10 Issue 1 Pages 60  
  Keywords European blackbirds; birds; Turdus merula; animals; melatonin; *Photoperiod  
  Abstract INTRODUCTION: Artificial light-at-night is known to affect a broad array of behaviours and physiological processes. In urbanized bird species, light-at-night advances important biological rhythms such as daily cycles of activity/rest and timing of reproduction, but our knowledge of the underlying physiological mechanisms is limited. Given its role as chronobiological signal, melatonin is a strong candidate for mediating the effects of light-at-night. RESULTS: We exposed urban and rural European blackbirds (Turdus merula) to two light treatments equal in photoperiod but with different light intensities at night. The control group was exposed to 0.0001 lux (almost darkness), while the experimental group was exposed to 0.3 lux at night, simulating conditions recorded previously on free-living urban blackbirds. We obtained diel profiles of plasma melatonin for all birds in summer (July) and winter (January), while simultaneously recording locomotor activity. Daily patterns of melatonin concentrations were clearly affected by light-at-night in both seasons. In winter, melatonin concentrations of light-at-night birds were lower in the early and late night than in those of birds kept in darkness. In summer, melatonin concentrations of the light-at-night birds were lower through all night compared to birds kept in darkness. Locomotor activity in light-at-night birds was overall higher than in control individuals, both during the day and at night, and it increased sharply before dawn. In winter, the amount of activity before dawn in the light-at-night group correlated with changes in melatonin from midnight to late night: the greater the decrease in melatonin, the greater the amount of pre-dawn activity. Urban and rural birds responded similarly to light-at-night with respect to melatonin, but differed in their behaviour, with rural birds showing more locomotor activity than urban counterparts. CONCLUSIONS: This study points to reduced melatonin release at night as a potential physiological mechanism underlying the advanced onset of morning activity of urbanized birds. Based on the pattern of melatonin secretion, we suggest that birds responded to light-at-night as if they were exposed to a longer day than birds kept under dark nights.  
  Address Department of Migration and Immuno-ecology, Max Planck Institute for Ornithology, Radolfzell, Germany. ddominoni@orn.mpg.de  
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  ISSN 1742-9994 ISBN Medium  
  Area Expedition Conference  
  Notes PMID:24090446; PMCID:PMC3850952 Approved no  
  Call Number IDA @ john @ Serial 41  
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