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Author Arendt, J.; Middleton, B.
Title Human seasonal and circadian studies in Antarctica (Halley, 75 degrees S) Type Journal Article
Year 2018 Publication General and Comparative Endocrinology Abbreviated Journal Gen Comp Endocrinol
Volume 258 Issue Pages 250-258
Keywords (up) Human Activities; Acclimatization/*physiology; Actigraphy; Adult; Antarctic Regions; Behavior/*physiology; Circadian Rhythm/*physiology; Darkness; Female; Heart Rate/physiology; Humans; Libido; Light; Male; Melatonin/blood; Photoperiod; *Seasons; Sleep/physiology; Young Adult; *Antarctica; *Circadian; *Light; *Melatonin; *Seasonal
Abstract Living for extended periods in Antarctica exposes base personnel to extremes of daylength (photoperiod) and temperature. At the British Antarctic Survey base of Halley, 75 degrees S, the sun does not rise for 110 d in the winter and does not set for 100 d in summer. Photoperiod is the major time cue governing the timing of seasonal events such as reproduction in many species. The neuroendocrine signal providing photoperiodic information to body physiology is the duration of melatonin secretion which reflects the length of the night: longer in the short days of winter and shorter in summer. Light of sufficient intensity and spectral composition serves to suppress production of melatonin and to set the circadian timing and the duration of the rhythm. In humans early observations suggested that bright (>2000 lux) white light was needed to suppress melatonin completely. Shortly thereafter winter depression (Seasonal Affective Disorder or SAD) was described, and its successful treatment by an artificial summer photoperiod of bright white light, sufficient to shorten melatonin production. At Halley dim artificial light intensity during winter was measured, until 2003, at a maximum of approximately 500 lux in winter. Thus a strong seasonal and circadian time cue was absent. It seemed likely that winter depression would be common in the extended period of winter darkness and could be treated with an artificial summer photoperiod. These observations, and predictions, inspired a long series of studies regarding human seasonal and circadian status, and the effects of light treatment, in a small overwintering, isolated community, living in the same conditions for many months at Halley. We found little evidence of SAD, or change in duration of melatonin production with season. However the timing of the melatonin rhythm itself, and/or that of its metabolite 6-sulphatoxymelatonin (aMT6s), was used as a primary marker of seasonal, circadian and treatment changes. A substantial phase delay of melatonin in winter was advanced to summer phase by a two pulse 'skeleton' bright white light treatment. Subsequently a single morning pulse of bright white light was effective with regard to circadian phase and improved daytime performance. The circadian delay evidenced by melatonin was accompanied by delayed sleep (logs and actigraphy): poor sleep is a common complaint in Polar regions. Appropriate extra artificial light, both standard white, and blue enriched, present throughout the day, effectively countered delay in sleep timing and the aMT6s rhythm. The most important factor appeared to be the maximum light experienced. Another manifestation of the winter was a decline in self-rated libido (men only on base at this time). Women on the base showed lower aspects of physical and mental health compared to men. Free-running rhythms were seen in some subjects following night shift, but were rarely found at other times, probably because this base has strongly scheduled activity and leisure time. Complete circadian adaptation during a week of night shift, also seen in a similar situation on North Sea oil rigs, led to problems readapting back to day shift in winter, compared to summer. Here again timed light treatment was used to address the problem. Sleep, alertness and waking performance are critically dependent on optimum circadian phase. Circadian desynchrony is associated with increased risk of major disease in shift workers. These studies provide some groundwork for countering/avoiding circadian desynchrony in rather extreme conditions.
Address Biochemistry and Physiology, Faculty of Health and Medical Sciences, University of Surrey, Guildford GU2 7XH, UK. Electronic address: b.middleton@surrey.ac.uk
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 0016-6480 ISBN Medium
Area Expedition Conference
Notes PMID:28526480 Approved no
Call Number IDA @ john @ Serial 2248
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Author Hall, A.L.; Davies, H.W.; Koehoorn, M.
Title Personal light-at-night exposures and components of variability in two common shift work industries: uses and implications for future research Type Journal Article
Year 2018 Publication Scandinavian Journal of Work, Environment & Health Abbreviated Journal Scand J Work Environ Health
Volume 44 Issue 1 Pages 80-87
Keywords (up) Human Health
Abstract Objectives Shift workers' increased risk of various adverse health outcomes has been linked to light-at-night (LAN) exposure, but few studies have measured LAN exposure in workplaces. To inform future research methods, this study aimed to (i) measure shift workers' exposures to LAN across industries, occupations, and work environments and (ii) assess components of variance across different exposure groupings and metrics. Methods Between October 2015 and March 2016, 152 personal full-shift measurements were collected from 102 night shift workers in emergency health services (paramedics, dispatchers) and healthcare industries (nurses, care aides, security guards, unit clerks, and laboratory, pharmacy, and respiratory therapy staff) in the province of British Columbia, Canada. Descriptive and variance component analyses were conducted for the 23:00-05:00 period to characterize exposures using multiple metrics of potential biological relevance (median lux, 90 thpercentile lux, sum of minutes >/=30 lux, and sum of minutes >/=100 lux). Results Average exposure levels were highest in the healthcare industry. By occupation, laboratory workers and care aides displayed the highest and emergency dispatch officers displayed the lowest levels for all LAN exposure metrics. Between-group variance was large relative to within-group variance for all exposure groupings and metrics, and increased as grouping specificity increased (moving from industry to occupation). Conclusions Results from this study suggest that high-level grouping schemes may provide a simple yet effective way of characterizing individual LAN exposures in epidemiological studies of shift work. Ongoing measurement of LAN exposures and assessment of exposure variability is needed in future studies of shift workers as a means to increase sampling efficiency, reduce measurement error, and maximize researchers' ability to detect relationships where they exist.
Address School of Population and Public Health, University of British Columbia, 2206 East Mall, Vancouver, V6T1Z3, Canada. amyhall@mail.ubc.ca
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 0355-3140 ISBN Medium
Area Expedition Conference
Notes PMID:28951937 Approved no
Call Number LoNNe @ kyba @ Serial 1754
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Author Souman, J.L.; Tinga, A.M.; Te Pas, S.F.; van Ee, R.; Vlaskamp, B.N.S.
Title Acute alerting effects of light: a systematic literature review Type Journal Article
Year 2018 Publication Behavioural Brain Research Abbreviated Journal Behav Brain Res
Volume 337 Issue Pages 228-239
Keywords (up) Human Health
Abstract Periodic, well timed exposure to light is important for our health and wellbeing. Light, in particular in the blue part of the spectrum, is thought to affect alertness both indirectly, by modifying circadian rhythms, and directly, giving rise to acute effects. We performed a systematic review of empirical studies on direct, acute effects of light on alertness to evaluate the reliability of these effects and to assess to what extent they depend on other factors, such as time of day, exposure duration and sleep pressure. In total, we identified 74 studies in which either light intensity, spectral distribution, or both were manipulated, and the effects on behavioral measures of alertness were evaluated, either subjectively or measured in performance tasks. The results show that increasing the intensity or the color temperature of polychromatic white light in general has been found to increase subjective ratings of alertness, though a substantial proportion of these studies failed to find significant effects. There is little evidence in the literature that these subjective alerting effects of light also translate into improvements on performance measures of alertness. For monochromatic or narrowband light exposure, some studies have shown improvement in reaction time tasks with exposure to blue light, but generally this was not accompanied by changes in subjective alertness. Thus, the alerting effects of light are far less clear than often suggested. We suggest that in future studies more attention should be paid to other factors that may influence the effects of light, such as chronotype, circadian phase, homeostatic state and prior light history.
Address Philips Research (Department Brain, Behavior & Cognition), Eindhoven, The Netherlands
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 0166-4328 ISBN Medium
Area Expedition Conference
Notes PMID:28912014 Approved no
Call Number LoNNe @ kyba @ Serial 1727
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Author Min, J.-young; Min, K.-bok
Title Outdoor light at night and the prevalence of depressive symptoms and suicidal behaviors: a cross-sectional study in a nationally representative sample of Korean adults Type Journal Article
Year 2018 Publication Journal of Affective Disorders Abbreviated Journal Journal of Affective Disorders
Volume 227 Issue Pages 199-205
Keywords (up) Human Health
Abstract Background

Outdoor light at night (LAN) is an increasingly prevalent type of environmental pollution. Studies have demonstrated that outdoor LAN can disrupt circadian rhythms, potentially contributing to insomnia, cancer, cardiovascular disease, and metabolic changes in humans. We investigated the association of outdoor LAN with depressive symptoms and suicidal behaviors in South Korean adults.

Methods

This study used data from the 2009 Korean Community Health Survey, a representative sample dataset. Study population consisted of 113,119 participants for the assessment of depressive symptoms and 152,159 participants for the assessment of suicidal behavior. Depressive symptoms were measured using the Korean version of the Center for Epidemiologic Studies Depression Scale (depressive symptoms, score of > 16). Suicidal behaviors were defined as the experience of suicidal ideation or attempt. Outdoor LAN was estimated by satellite data from the National Centers for Environmental Information.

Results

Participants with depressive symptoms or history of suicidal behaviors were more likely to have exposure to outdoor LAN than those without depressive symptoms or suicidal behaviors. Compared with adults living in areas exposed to the lowest outdoor LAN, those living in areas exposed to the highest levels had higher likelihood depressive symptoms (OR = 1.29; 95% CI: 1.15–1.46) or suicidal behaviors (OR = 1.27; 95% CI: 1.16–1.39). Significant dose-response relationships were observed between outdoor LAN and the odds of depressive symptoms and suicidal behaviors.

Conclusion

Outdoor LAN was found to be significantly associated with depressive symptoms and suicidal behaviors, suggesting that it may be an environmental contributor to mental health problems.
Address
Corporate Author Thesis
Publisher Place of Publication Editor
Language Summary Language Original Title
Series Editor Series Title Abbreviated Series Title
Series Volume Series Issue Edition
ISSN 0165-0327 ISBN Medium
Area Expedition Conference
Notes Approved no
Call Number LoNNe @ kyba @ Serial 1777
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Author Kozaki, Tomoaki; Taketomi, Ryunosuke; Hidaka ,Yuki; Ida, Nagisa; Yasuda, Takeo
Title Preventive Effect of Morning Bluish LED Light on Light-induced Melatonin Suppression at Night Type Journal Article
Year 2018 Publication Journal of Science and Technology in Lighting Abbreviated Journal
Volume 41 Issue Pages 206-210
Keywords (up) Human Health
Abstract Bright nocturnal light has been known to suppress melatonin secretion. However, bright light exposure during daytime might reduce light-induced melatonin suppression (LIMS) at night. This study aims to evaluate the effect of high correlated color temperature LED light during daytime on LIMS. Male participants were exposed to different light conditions for 3 h in the morning (09:00â??12:00). The light conditions were dim light (<10 lx), 125 lx high correlated color temperature (CCT) LED light, and 250 lx high CCT LED light. The subjects were then exposed to bright light (white light, 300 lx) for 1.5 h at night (01:00â??02:30). Saliva samples were taken before (01:00) and after (02:30) exposure for evaluation of melatonin secretion. There were no significant differences in melatonin secretion before and after night-time light exposure on the 125 lx and 250 lx morning light conditions. Since these light intensities were almost equal to those in our previous study, the high CCT LED light might be appropriate for certain work places (e.g., hospitals and underground spaces), contributing to the reduction of our health risk and also saving energy.
Address
Corporate Author Thesis
Publisher Place of Publication Editor
Language Summary Language Original Title
Series Editor Series Title Abbreviated Series Title
Series Volume Series Issue Edition
ISSN ISBN Medium
Area Expedition Conference
Notes Approved no
Call Number LoNNe @ kyba @ Serial 1785
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