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Author Mortazavi, S.A.R., Parhoodeh, S., Hosseini, M.A., Arabi, H., Malakooti, H., Nematollahi, S., Mortazavi, G., Darvish, L., Mortazavi, S.M.J.
Title (up) Blocking Short-Wavelength Component of the Visible Light Emitted by Smartphones’ Screens Improves Human Sleep Quality Type Journal Article
Year 2018 Publication Journal of Biomedical Physics and Engineering Abbreviated Journal
Volume 8 Issue 4 Pages 375-380
Keywords Human Health
Abstract Background: It has been shown that short-wavelength blue component of the visible light spectrum can alter the circadian rhythm and suppress the level of melatonin hormone. The short-wavelength light emitted by smartphones’ screens can affect the sleep quality of the people who use these devices at night through suppression of melatonin.

Objectives: In this study, we examined the effects of covering the screens of smartphones with different filters (changing the effective wavelength of the light) on sleep delay time in 43 healthy students.

Materials and Methods: Volunteer students were asked to go to bed at 23:00 and to use their mobile phones in bed for watching a natural life documentary movie for 60 minutes. No filter was used for one night while amber and blue filters were used for other 2 nights. Photospectrometry method was used to determine the output spectrum of the light passing through the filters used for covering the screens of the mobile phones. The order for utilizing amber or blue filters or using no filter was selected randomly. After 1 hour, the participants were asked to record their sleep delay time measured by a modified form of sleep time record sheet.

Results: The mean sleep delay time for the “no-filter” night was 20.84±9.15 minutes, while the sleep delay times for the nights with amber and blue filters were 15.26±1.04 and 26.33±1.59 minutes, respectively.

Conclusion: The findings obtained in this study support this hypothesis that blue light possibly suppresses the secretion of melatonin more than the longer wavelengths of the visible light spectrum. Using amber filter in this study significantly improved the sleep quality. Altogether, these findings lead us to this conclusion that blocking the short-wavelength component of the light emitted by smartphones’ screens improves human sleep.
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Call Number NC @ ehyde3 @ Serial 2077
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Author Brelsford, CC; Robson, TM
Title (up) Blue light advances bud burst in branches of three deciduous tree species under short-day conditions Type Journal Article
Year 2018 Publication Trees Abbreviated Journal
Volume 32 Issue 4 Pages 1157-1164
Keywords Plants
Abstract During spring, utilising multiple cues allow tree species from temperate and boreal regions to coordinate their bud burst and leaf out, at the right moment to capitalise on favourable conditions for photosynthesis. Whilst the effect of blue light (400–500 nm) has been shown to increase percentage bud burst of axillary shoots of Rosa sp., the effects of blue light on spring-time bud burst of deciduous tree species have not previously been reported. We tested the hypotheses that blue light would advance spring bud burst in tree species, and that late-successional species would respond more than early-successional species, whose bud burst is primarily determined by temperature. The bud development of Alnus glutinosa, Betula pendula, and Quercus robur branches, cut from dormant trees, was monitored under two light treatments of equal photosynthetically active radiation (PAR, 400–700 nm) and temperature, either with or without blue light, under controlled environmental conditions. In the presence of blue light, the mean time required to reach 50% bud burst was reduced by 3.3 days in Betula pendula, 6 days in Alnus glutinosa, and 6.3 days in Quercus robur. This result highlights the potential of the blue region of the solar spectrum to be used as an extra cue that could help plants to regulate their spring phenology, alongside photoperiod and temperature. Understanding how plants combine photoreceptor-mediated cues with other environmental cues such as temperature to control phenology is essential if we are to accurately predict how tree species might respond to climate change.
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Call Number GFZ @ kyba @ Serial 1847
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Author Zhao, X.; Zhang M.; Che, X.; Zou, F.
Title (up) Blue light attracts nocturnally migrating birds Type Journal Article
Year 2020 Publication The Condor Abbreviated Journal
Volume in press Issue Pages in press
Keywords Animals
Abstract Light pollution is increasing and artificial light sources have great impacts on animals. For migrating birds, collisions caused by artificial light pollution are a significant source of mortality. Laboratory studies have demonstrated that birds have different visual sensitivities to different colors of light, but few field experiments have compared birds’ responses to light of different wavelengths. We used 3 monochromatic lights (red, green, and blue) and polychromatic yellow light to study the impact of wavelength on phototaxis at 2 gathering sites of nocturnally migrating birds in Southwest China. For both sites, short-wavelength blue light caused the strongest phototactic response. In contrast, birds were rarely attracted to long-wavelength red light. The attractive effect of blue light was greatest during nights with fog and headwinds. As rapid urbanization and industrialization cause an increase in artificial light, we suggest that switching to longer wavelength lights is a convenient and economically effective way to reduce bird collisions.

摘要

目前地球上光污染日益严重,五颜六色的人工光源对生态系统造成了很大影响。就鸟类而言,在世界各地已发生了很多鸟类撞击人工光源的事件。实验室研究表明,鸟类对不同颜色的光有不同的视觉敏感度,但很少有野外实验比较鸟类对不同波长光的反应。我们在中国西南地区的两个夜间候鸟迁徙聚集点使用三种单色光(红、绿、蓝)和一种复合光(黄),研究了光波长对的候鸟趋光性的影响。研究表明,短波长的蓝光引起了候鸟最强烈的趋光性反应。相反,鸟类很少被长波长的红光所吸引。特别是在有雾和逆风的夜晚,蓝光的吸引力最大。由于快速的城市化和工业化导致人造光的增加,我们认为使用长波光是一个减少鸟类碰撞光源的方便和经济有效的方式。
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Call Number GFZ @ kyba @ Serial 2896
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Author Dong, K.; Goyarts, E.C.; Pelle, E.; Trivero, J.; Pernodet, N.
Title (up) Blue Light disrupts the circadian rhythm and create damage in skin cells Type Journal Article
Year 2019 Publication International Journal of Cosmetic Science Abbreviated Journal Int J Cosmet Sci
Volume 41 Issue 6 Pages 558-562
Keywords Human Health; Circadian disruption; Skin; Clock genes
Abstract On a daily basis, the skin is exposed to many environmental stressors and insults. Over a 24-hr natural cycle, during the day, the skin is focused on protection; while at night, the skin is focused on repairing damage that occurred during daytime and getting ready for the next morning. Circadian rhythm provides the precise timing mechanism for engaging those different pathways necessary to keep a healthy skin through clock genes that are present in all skin cells. The strongest clue for determining cellular functions timing is through sensing light or absence of light (darkness). Here, we asked the question if blue light could be a direct entrainment signal to skin cells and also disrupt their circadian rhythm at night. Through a reporter assay for per1 transcription, we demonstrate that blue light at 410nm decreases per1 transcription in keratinocytes, showing that epidermal skin cells can sense light directly and control their own clock gene expression. This triggers cells to “think” it is daytime even at nighttime. Elsewhere, we measured different skin cell damage due to blue light exposure (at different doses and times of exposure) versus cells that were kept in full darkness. We show an increase of ROS production, DNA damage and inflammatory mediators. These deleterious effects can potentially increase overall skin damage over time and ultimately accelerates aging.
Address Materials Science & Engineering, Stony Brook University, Stony Brook
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Language English Summary Language Original Title
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ISSN 0142-5463 ISBN Medium
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Notes PMID:31418890 Approved no
Call Number GFZ @ kyba @ Serial 2618
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Author Stern, M.; Broja, M.; Sansone, R.; Grone, M.; Skene, S.S.; Liebmann, J.; Suschek, C.V.; Born, M.; Kelm, M.; Heiss, C.
Title (up) Blue light exposure decreases systolic blood pressure, arterial stiffness, and improves endothelial function in humans Type Journal Article
Year 2018 Publication European Journal of Preventive Cardiology Abbreviated Journal Eur J Prev Cardiol
Volume 25 Issue 17 Pages 1875-1883
Keywords Human Health; Blue light; blood pressure; endothelial function; forearm blood flow; pulse wave velocity
Abstract AIMS: Previous studies have shown that ultraviolet light can lead to the release of nitric oxide from the skin and decrease blood pressure. In contrast to visible light the local application of ultraviolet light bears a cancerogenic risk. Here, we investigated whether whole body exposure to visible blue light can also decrease blood pressure and increase endothelial function in healthy subjects. METHODS: In a randomised crossover study, 14 healthy male subjects were exposed on 2 days to monochromatic blue light or blue light with a filter foil (control light) over 30 minutes. We measured blood pressure (primary endpoint), heart rate, forearm vascular resistance, forearm blood flow, endothelial function (flow-mediated dilation), pulse wave velocity and plasma nitric oxide species, nitrite and nitroso compounds (secondary endpoints) during and up to 2 hours after exposure. RESULTS: Blue light exposure significantly decreased systolic blood pressure and increased heart rate as compared to control. In parallel, blue light significantly increased forearm blood flow, flow-mediated dilation, circulating nitric oxide species and nitroso compounds while it decreased forearm vascular resistance and pulse wave velocity. CONCLUSION: Whole body irradiation with visible blue light at real world doses improves blood pressure, endothelial function and arterial stiffness by nitric oxide released from photolabile intracutanous nitric oxide metabolites into circulating blood.
Address Department of Clinical and Experimental Medicine, Faculty of Health and Medical Sciences, University of Surrey, Stag Hill, Guildford GU2 7XH, UK. Email: c.heiss(at)
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Publisher SAGE Place of Publication Editor
Language English Summary Language English Original Title
Series Editor Series Title Abbreviated Series Title
Series Volume Series Issue Edition
ISSN 2047-4873 ISBN Medium
Area Expedition Conference
Notes PMID:30196723 Approved no
Call Number IDA @ john @ Serial 2157
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