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Author (up) Ikeda, Masayuki; Sagara, Masami; Inoué, Shojiro
Title Continuous exposure to dim illumination uncouples temporal patterns of sleep, body temperature, locomotion and drinking behavior in the rat Type Journal Article
Year 2000 Publication Neuroscience Letters Abbreviated Journal
Volume 279 Issue 3 Pages 185-189
Keywords animals; rodents; animal behaviour
Abstract Dissociable circadian rhythms of sleep and body temperature in primates are thought to be regulated by independent oscillators whereas the uncoupling of circadian rhythms has not been well described in other mammals. Therefore, we made simultaneous recordings of non-rapid-eye-movement-sleep (NREMS), rapid-eye-movement-sleep (REMS), brain temperature, intraperitoneal temperature, locomotion and drinking activity under light-dark (LD) and continuous dim illumination (dim LL) and analyzed their interrelations. The rhythmic patterns of body temperature, locomotion and drinking were modified on the 12th circadian day of dim LL, while the mean body temperature as well as mean occurrence of drinking and locomotor activities did not change significantly. In contrast, dim LL exposure significantly increased the total time spent in NREMS during the resting phase of dim LL and increased REMS episodes during the active phase of dim LL. The diverse effects of dim LL exposure on the recorded phenomena suggest that temporal patterns of sleep were the most sensitive to perturbations of lighting and that differential oscillatory mechanisms may regulate sleep and other circadian rhythms in the rat.
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Call Number LoNNe @ schroer @ Serial 1591
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Author (up) Kozaki, T.; Hidaka, Y.; Takakura, J.-Y.; Kusano, Y.
Title Salivary melatonin suppression under 100-Hz flickering blue light and non-flickering blue light conditions Type Journal Article
Year 2020 Publication Neuroscience Letters Abbreviated Journal Neurosci Lett
Volume 722 Issue Pages 134857
Keywords Human Health; Flickering light; Intrinsically photosensitive retinal ganglion cell; Light; Light emitting diode; Melatonin
Abstract Bright light at night has been known to suppress melatonin secretion. Photoreceptors, known as intrinsically photosensitive retinal ganglion cells (ipRGCs), project dark/bright information into the superchiasmatic nucleus, which regulates the circadian system. Electroretinograms of ipRGCs show fluctuation that is synchronized with light ON-OFF stimulation. This finding suggests that the flickering condition of light may have an impact on our circadian system. In this study, we evaluate light-induced melatonin suppression under flickering and non-flickering light conditions. Fifteen male subjects between the ages of 20 and 23 years (mean +/- SD, 21.9 +/- 1.9) were exposed to three light conditions (dim, 100-Hz flickering and non-flickering light) from 1:00 a.m. to 2:30 a.m. Saliva samples were taken just before 1:00 and at 1:15, 1:30, 2:00, and 2:30 a.m. Repeated-measure t-test with Bonferroni correction showed a significant decrease in melatonin levels under both 100-Hz and non-flickering light conditions compared to dim light conditions after 2:00 a.m. Moreover, at 2:30 a.m., the rate of change in melatonin level under 100 Hz of flickering light was significantly lower than that under non-flickering light. Our present findings suggest that 100-Hz flickering light may suppress melatonin secretion more than non-flickering light.
Address Department of Health and Nutrition Sciences, Nishikyushu University, 4490-9 Osaki, Kanzaki, Japan
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ISSN 0304-3940 ISBN Medium
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Notes PMID:32097701 Approved no
Call Number GFZ @ kyba @ Serial 2855
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Author (up) Middleton, B.; Stone, B.M.; Arendt, J.
Title Human circadian phase in 12:12 h, 200:<8 lux and 1000:<8 lux light-dark cycles, without scheduled sleep or activity Type Journal Article
Year 2002 Publication Neuroscience Letters Abbreviated Journal Neuroscience Letters
Volume 329 Issue 1 Pages 41-44
Keywords Human Health
Abstract The light levels required to maintain human circadian phase in the absence of other strong time cues are not defined. We investigated circadian phase in two groups of men, living in partial temporal isolation, exposed to 12 h:12 h light:dark cycles of: (A) 200:<8 lux, broad spectrum white light for 14 days; and (B) 1000:<8lux for 14 days. The rhythm variables measured were urinary 6-sulphatoxymelatonin, rectal temperature, activity and rest (actigraphy and sleep logs). In 200:<8 lux four/six individuals showed phase delays. Exposure to 1000:<8 lux appeared to maintain synchronisation of rest-activity to 24 h, but with a significant overall phase advance of 0.81 h in temperature. These observations suggest that domestic intensity light does not maintain phase without scheduled sleep/activity, possibly due to indirect effects on behaviour influencing light exposure.
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Notes Approved no
Call Number GFZ @ kyba @ Serial 2247
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Author (up) Moaraf, S.; Vistoropsky, Y.; Pozner, T.; Heiblum, R.; Okuliarova, M.; Zeman, M.; Barnea, A.
Title Artificial light at night affects brain plasticity and melatonin in birds Type Journal Article
Year 2019 Publication Neuroscience Letters Abbreviated Journal Neurosci Lett
Volume in press Issue Pages 134639
Keywords Animals; Artificial Light At Night (ALAN); cell proliferation; circadian cycle; melatonin; neuronal densities; zebra finches (Taeniopygia guttata)
Abstract Artificial light at night (ALAN), which disrupts the daily cycle of light, has vast biological impacts on all organisms, and is also associated with several health problems. The few existing studies on neuronal plasticity and cognitive functions in mammals indicate that a disruption of the circadian cycle impairs learning and memory and suppresses neurogenesis. However, nothing is known about the effect of ALAN on neuronal plasticity in birds. To this end, zebra finches (Taeniopygia guttata) were exposed to ecologically relevant ALAN intensities (0.5, 1.5 and 5 lux), treated with BrdU to quantify cell proliferation in their ventricular zone (VZ), and compared to controls that were kept under dark nights. We found, in our diurnal birds, that ALAN significantly increased cell proliferation in the VZ. However, neuronal densities in two brain regions decreased under ALAN, suggesting neuronal death. In addition, ALAN suppressed nocturnal melatonin production in a dose-dependent manner, and might also increase body mass. Taken together, our findings add to the notion of the deleterious effect of ALAN.
Address Department of Natural and Life Sciences, The Open University of Israel, Ra'anana, 43107, Israel
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ISSN 0304-3940 ISBN Medium
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Notes PMID:31760086 Approved no
Call Number GFZ @ kyba @ Serial 2760
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