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Author Kavcic, P.; Rojc, B.; Dolenc-Groselj, L.; Claustrat, B.; Fujs, K.; Poljak, M.
Title The impact of sleep deprivation and nighttime light exposure on clock gene expression in humans Type Journal Article
Year 2011 Publication Croatian Medical Journal Abbreviated Journal Croat Med J
Volume 52 Issue 5 Pages 594-603
Keywords genomics; epigenetics; hPer2; hBmal1; clock genes; gene expression; biology; human health
Abstract Aim

To examine the effect of acute sleep deprivation under light conditions on the expression of two key clock genes, hPer2 and hBmal1, in peripheral blood mononuclear cells (PBMC) and on plasma melatonin and cortisol levels.

Methods

Blood samples were drawn from 6 healthy individuals at 4-hour intervals for three consecutive nights, including a night of total sleep deprivation (second night). The study was conducted in April-June 2006 at the University Medical Centre Ljubljana.

Results

We found a significant diurnal variation in hPer2 and hBmal1 expression levels under baseline (P < 0.001, F = 19.7, df = 30 for hPer2 and P < 0.001, F = 17.6, df = 30 for hBmal1) and sleep-deprived conditions (P < 0.001, F = 9.2, df = 30 for hPer2 and P < 0.001, F = 13.2, df = 30 for hBmal1). Statistical analysis with the single cosinor method revealed circadian variation of hPer2 under baseline and of hBmal1 under baseline and sleep-deprived conditions. The peak expression of hPer2 was at 13:55 ± 1:15 hours under baseline conditions and of hBmal1 at 16:08 ± 1:18 hours under baseline and at 17:13 ± 1:35 hours under sleep-deprived conditions. Individual cosinor analysis of hPer2 revealed a loss of circadian rhythm in 3 participants and a phase shift in 2 participants under sleep-deprived conditions. The plasma melatonin and cortisol rhythms confirmed a conventional alignment of the central circadian pacemaker to the habitual sleep/wake schedule.

Conclusion

Our results suggest that 40-hour acute sleep deprivation under light conditions may affect the expression of hPer2 in PBMCs.
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Publisher Place of Publication Editor
Language Summary Language Original Title
Series Editor Series Title Abbreviated Series Title
Series Volume Series Issue Edition
ISSN 0353-9504 ISBN Medium
Area Expedition Conference
Notes Approved no
Call Number IDA @ john @ Serial 135
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Author Reiter, R.; Tan, D.; SanchezBarcelo, E.; Mediavilla, M.; Gitto, E.; Korkmaz, A.
Title Circadian mechanisms in the regulation of melatonin synthesis: disruption with light at night and the pathophysiological consequences Type Journal Article
Year 2011 Publication Journal of Experimental and Integrative Medicine Abbreviated Journal J Exp Integr Med
Volume 1 Issue 1 Pages 13
Keywords Human Health
Abstract In the past two decades, the results of a number of epidemiological studies have uncovered an association between excessive light exposure at night and the prevalence of cancer. Whereas the evidence supporting this link is strongest between nighttime light and female breast and male prostate cancer, the frequency of other tumor types may also be elevated. Individuals who have the highest reported increase in cancer are chronic night shift workers and flight attendants who routinely fly across numerous time zones.

There are at least two obvious physiological consequences of nighttime light exposure, i.e., a reduction in circulating melatonin levels and disruption of the circadian system (chronodisruption). Both these perturbations in experimental animals aggravate tumor growth. Melatonin has a long investigative history in terms of its ability to stymie the growth of many tumor types. Likewise, in the last decade chronodisruption has been unequivocally linked to a variety of abnormal metabolic conditions including excessive tumor growth.

This brief review summarizes the processes by which light after darkness onset impedes melatonin production and disturbs circadian rhythms. The survey also reviews the evidence associating the ostensible danger of excessive nighttime light pollution to cancer risk. If an elevated tumor frequency is definitively proven to be a consequence of light at night and/or chronodisruption, it seems likely that cancer will not be the exclusive pathophysiological change associated with the rampant light pollution characteristic of modern societies.
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Publisher Place of Publication Editor
Language Summary Language Original Title
Series Editor Series Title Abbreviated Series Title
Series Volume Series Issue Edition
ISSN 1309-4572 ISBN Medium
Area Expedition Conference
Notes Approved no
Call Number IDA @ john @ Serial 137
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Author Hurley, S.; Nelson, D.O.; Garcia, E.; Gunier, R.; Hertz, A.; Reynolds, P.
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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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:24127816; PMCID:PMC3766028 Approved no
Call Number IDA @ john @ Serial 142
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Author Kretschmer, V.; Schmidt, K.-H.; Griefahn, B.
Title Bright light effects on working memory, sustained attention and concentration of elderly night shift workers Type Journal Article
Year 2012 Publication Lighting Research and Technology Abbreviated Journal Lighting Research and Technology
Volume 44 Issue 3 Pages 316-333
Keywords shift work; light at night; light exposure; memory; concentration; human health
Abstract Night shift workers show a decline in performance during working time. Due to demographic change, the labour market requires more elderly people to work at night. Ageing is accompanied by a decrease in cognitive abilities, in the capabilities of the visual system and in coping with night work from the age of 40 onwards. This investigation focuses on the effects of bright light exposure on the working memory, concentration and sustained attention of elderly persons during three consecutive night shifts. After statistical control for neuroticism and intelligence as covariates, the results demonstrate that exposure to bright light at night reduces error rates for a working memory task and a concentration performance task but performance on a sustained attention task is completely unaffected.
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Publisher Place of Publication Editor
Language Summary Language Original Title
Series Editor Series Title Abbreviated Series Title
Series Volume Series Issue Edition
ISSN 1477-1535 ISBN Medium
Area Expedition Conference
Notes Approved no
Call Number IDA @ john @ Serial 147
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Author Evans, J.A.; Elliott, J.A.; Gorman, M.R.
Title Dim nighttime illumination accelerates adjustment to timezone travel in an animal model Type Journal Article
Year 2009 Publication Current Biology : CB Abbreviated Journal Curr Biol
Volume 19 Issue 4 Pages R156-7
Keywords *Adaptation, Physiological; Animals; Behavior, Animal/physiology; Biological Clocks/*physiology; Circadian Rhythm/*physiology; Cricetinae; Humans; *Lighting; Mesocricetus; Mice; Motor Activity/physiology; Phodopus; *Photoperiod; Time Factors
Abstract Jetlag reflects a mismatch between local and circadian time following rapid timezone travel [1]. Appropriately timed bright light can shift human circadian rhythms but recovery is slow (e.g., 1-2 days per timezone). Most symptoms subside after resynchronization, but chronic jetlag may have enduring negative effects [2], including even accelerated mortality in mice [3]. Melatonin, prescription drugs, and/or exercise may help shift the clock but, like bright light, require complex schedules of application [1]. Thus, there is a need for more efficient and practical treatments for addressing jetlag. In contrast to bright daytime lighting, nighttime conditions have received scant attention. By incorporating more naturalistic nighttime lighting comparable in intensity to dim moonlight, we demonstrate that recovery after simulated jetlag is accelerated when nights are dimly lit rather than completely dark.
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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:19243688 Approved no
Call Number IDA @ john @ Serial 152
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