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Author (up) Brainard, G.C.; Sliney, D.; Hanifin, J.P.; Glickman, G.; Byrne, B.; Greeson, J.M.; Jasser, S.; Gerner, E.; Rollag, M.D.
Title Sensitivity of the human circadian system to short-wavelength (420-nm) light Type Journal Article
Year 2008 Publication Journal of Biological Rhythms Abbreviated Journal J Biol Rhythms
Volume 23 Issue 5 Pages 379-386
Keywords Human Health; Adult; Circadian Rhythm/*radiation effects; Female; Humans; *Light; Male; Melatonin/metabolism; Models, Biological; Neurosecretory Systems; Photons; Pineal Gland/metabolism; Retinal Ganglion Cells/*metabolism; Vision, Ocular
Abstract The circadian and neurobehavioral effects of light are primarily mediated by a retinal ganglion cell photoreceptor in the mammalian eye containing the photopigment melanopsin. Nine action spectrum studies using rodents, monkeys, and humans for these responses indicate peak sensitivities in the blue region of the visible spectrum ranging from 459 to 484 nm, with some disagreement in short-wavelength sensitivity of the spectrum. The aim of this work was to quantify the sensitivity of human volunteers to monochromatic 420-nm light for plasma melatonin suppression. Adult female (n=14) and male (n=12) subjects participated in 2 studies, each employing a within-subjects design. In a fluence-response study, subjects (n=8) were tested with 8 light irradiances at 420 nm ranging over a 4-log unit photon density range of 10(10) to 10(14) photons/cm(2)/sec and 1 dark exposure control night. In the other study, subjects (n=18) completed an experiment comparing melatonin suppression with equal photon doses (1.21 x 10(13) photons/cm(2)/sec) of 420 nm and 460 nm monochromatic light and a dark exposure control night. The first study demonstrated a clear fluence-response relationship between 420-nm light and melatonin suppression (p<0.001) with a half-saturation constant of 2.74 x 10(11) photons/cm(2)/sec. The second study showed that 460-nm light is significantly stronger than 420-nm light for suppressing melatonin (p<0.04). Together, the results clarify the visible short-wavelength sensitivity of the human melatonin suppression action spectrum. This basic physiological finding may be useful for optimizing lighting for therapeutic and other applications.
Address Department of Neurology, Thomas Jefferson University, Philadelphia, PA 19107, USA. george.brainard@jefferson.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 0748-7304 ISBN Medium
Area Expedition Conference
Notes PMID:18838601 Approved no
Call Number LoNNe @ kagoburian @ Serial 724
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Author (up) Daneault, V.; Vandewalle, G.; Hebert, M.; Teikari, P.; Mure, L.S.; Doyon, J.; Gronfier, C.; Cooper, H.M.; Dumont, M.; Carrier, J.
Title Does pupil constriction under blue and green monochromatic light exposure change with age? Type Journal Article
Year 2012 Publication Journal of Biological Rhythms Abbreviated Journal J Biol Rhythms
Volume 27 Issue 3 Pages 257-264
Keywords Human Health
Abstract Many nonvisual functions are regulated by light through a photoreceptive system involving melanopsin-expressing retinal ganglion cells that are maximally sensitive to blue light. Several studies have suggested that the ability of light to modulate circadian entrainment and to induce acute effects on melatonin secretion, subjective alertness, and gene expression decreases during aging, particularly for blue light. This could contribute to the documented changes in sleep and circadian regulatory processes with aging. However, age-related modification in the impact of light on steady-state pupil constriction, which regulates the amount of light reaching the retina, is not demonstrated. We measured pupil size in 16 young (22.8+/-4 years) and 14 older (61+/-4.4 years) healthy subjects during 45-second exposures to blue (480 nm) and green (550 nm) monochromatic lights at low (7x10(12) photons/cm2/s), medium (3x10(13) photons/cm2/s), and high (10(14) photons/cm2/s) irradiance levels. Results showed that young subjects had consistently larger pupils than older subjects for dark adaptation and during all light exposures. Steady-state pupil constriction was greater under blue than green light exposure in both age groups and increased with increasing irradiance. Surprisingly, when expressed in relation to baseline pupil size, no significant age-related differences were observed in pupil constriction. The observed reduction in pupil size in older individuals, both in darkness and during light exposure, may reduce retinal illumination and consequently affect nonvisual responses to light. The absence of a significant difference between age groups for relative steady-state pupil constriction suggests that other factors such as tonic, sympathetic control of pupil dilation, rather than light sensitivity per se, account for the observed age difference in pupil size regulation. Compared to other nonvisual functions, the light sensitivity of steady-state pupil constriction appears to remain relatively intact and is not profoundly altered by age.
Address Functional Neuroimaging Unit, University of Montreal Geriatric Institute, and Center for Advanced Research in Sleep Medicine, Hopital du Sacre-Coeur de Montreal, Montreal, QC, Canada
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 0748-7304 ISBN Medium
Area Expedition Conference
Notes PMID:22653894 Approved no
Call Number LoNNe @ kyba @ Serial 1621
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Author (up) de Jong, M.; Caro, S.P.; Gienapp, P.; Spoelstra, K.; Visser, M.E.
Title Early Birds by Light at Night: Effects of Light Color and Intensity on Daily Activity Patterns in Blue Tits Type Journal Article
Year 2017 Publication Journal of Biological Rhythms Abbreviated Journal J Biol Rhythms
Volume 32 Issue 4 Pages 323-333
Keywords Animals
Abstract Artificial light at night disturbs the daily rhythms of many organisms. To what extent this disturbance depends on the intensity and spectral composition of light remain obscure. Here, we measured daily activity patterns of captive blue tits ( Cyanistes caeruleus) exposed to similar intensities of green, red, or white light at night. Birds advanced their onset of activity in the morning under all light colors but more under red and white light than under green light. Offset of activity was slightly delayed in all light colors. The total activity over a 24-h period did not change but birds moved a part of their daily activity into the night. Since the effect of red and white lights are comparable, we tested the influence of light intensity in a follow-up experiment, where we compared the activity of the birds under different intensities of green and white light only. While in the higher range of intensities, the effects of white and green light were comparable; at lower intensities, green light had a less disturbing effect as compared with white light on daily rhythms in blue tits. Our results show that the extent of this disturbance can be mitigated by modulating the spectral characteristics and intensity of outdoor lighting, which is now feasible through the use of LED lighting.
Address Netherlands Institute of Ecology (NIOO-KNAW), Department of Animal Ecology, Wageningen, The Netherlands
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ISSN 0748-7304 ISBN Medium
Area Expedition Conference
Notes PMID:28745147 Approved no
Call Number GFZ @ kyba @ Serial 1863
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Author (up) de la Iglesia, H.O.; Fernandez-Duque, E.; Golombek, D.A.; Lanza, N.; Duffy, J.F.; Czeisler, C.A.; Valeggia, C.R.
Title Access to Electric Light Is Associated with Shorter Sleep Duration in a Traditionally Hunter-Gatherer Community Type Journal Article
Year 2015 Publication Journal of Biological Rhythms Abbreviated Journal J Biol Rhythms
Volume 30 Issue 4 Pages 342-350
Keywords Human health
Abstract Access to electric light might have shifted the ancestral timing and duration of human sleep. To test this hypothesis, we studied two communities of the historically hunter-gatherer indigenous Toba/Qom in the Argentinean Chaco. These communities share the same ethnic and sociocultural background, but one has free access to electricity while the other relies exclusively on natural light. We fitted participants in each community with wrist activity data loggers to assess their sleep-wake cycles during one week in the summer and one week in the winter. During the summer, participants with access to electricity had a tendency to a shorter daily sleep bout (43 +/- 21 min) than those living under natural light conditions. This difference was due to a later daily bedtime and sleep onset in the community with electricity, but a similar sleep offset and rise time in both communities. In the winter, participants without access to electricity slept longer (56 +/- 17 min) than those with access to electricity, and this was also related to earlier bedtimes and sleep onsets than participants in the community with electricity. In both communities, daily sleep duration was longer during the winter than during the summer. Our field study supports the notion that access to inexpensive sources of artificial light and the ability to create artificially lit environments must have been key factors in reducing sleep in industrialized human societies.
Address Department of Anthropology, Yale University, New Haven, Connecticut, USA horaciod@uw.edu claudia.valeggia@yale.edu
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ISSN 0748-7304 ISBN Medium
Area Expedition Conference
Notes PMID:26092820 Approved no
Call Number LoNNe @ christopher.kyba @ Serial 1188
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Author (up) Evans, J.A.; Elliott, J.A.; Gorman, M.R.
Title Circadian effects of light no brighter than moonlight Type Journal Article
Year 2007 Publication Journal of Biological Rhythms Abbreviated Journal J Biol Rhythms
Volume 22 Issue 4 Pages 356-367
Keywords Animals; Biological Clocks/physiology/*radiation effects; *Circadian Rhythm; Cricetinae; Dose-Response Relationship, Radiation; Lighting/*methods; Male; Mesocricetus; Motor Activity; Oscillometry; Photic Stimulation/methods; *Photoperiod; Physical Conditioning, Animal; Time Factors
Abstract In mammals, light entrains endogenous circadian pacemakers by inducing daily phase shifts via a photoreceptor mechanism recently discovered in retinal ganglion cells. Light that is comparable in intensity to moonlight is generally ineffective at inducing phase shifts or suppressing melatonin secretion, which has prompted the view that circadian photic sensitivity has been titrated so that the central pacemaker is unaffected by natural nighttime illumination. However, the authors have shown in several different entrainment paradigms that completely dark nights are not functionally equivalent to dimly lit nights, even when nighttime illumination is below putative thresholds for the circadian visual system. The present studies extend these findings. Dim illumination is shown here to be neither a strong zeitgeber, consistent with published fluence response curves, nor a potentiator of other zeitgebers. Nevertheless, dim light markedly alters the behavior of the free-running circadian pacemaker. Syrian hamsters were released from entrained conditions into constant darkness or dim narrowband green illumination (~0.01 lx, 1.3 x 10(-9) W/cm(2), peak lambda = 560 nm). Relative to complete darkness, constant dim light lengthened the period by ~0.3 h and altered the waveform of circadian rhythmicity. Among animals transferred from long day lengths (14 L:10 D) into constant conditions, dim illumination increased the duration of the active phase (alpha) by ~3 h relative to complete darkness. Short day entrainment (8 L:16 D) produced initially long alpha that increased further under constant dim light but decreased under complete darkness. In contrast, dim light pulses 2 h or longer produced effects on circadian phase and melatonin secretion that were small in magnitude. Furthermore, the amplitude of phase resetting to bright light and nonphotic stimuli was similar against dimly lit and dark backgrounds, indicating that the former does not directly amplify circadian inputs. Dim illumination markedly alters circadian waveform through effects on alpha, suggesting that dim light influences the coupling between oscillators theorized to program the beginning and end of subjective night. Physiological mechanisms responsible for conveying dim light stimuli to the pacemaker and implications for chronotherapeutics warrant further study.
Address Department of Psychology, University of California, San Diego, La Jolla, CA 92093, usa. jaevans@ucsd.edu
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Language English Summary Language Original Title
Series Editor Series Title Abbreviated Series Title
Series Volume Series Issue Edition
ISSN 0748-7304 ISBN Medium
Area Expedition Conference
Notes PMID:17660452 Approved no
Call Number IDA @ john @ Serial 31
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