| Records |
| Author |
Porcheret, K.; Wald, L.; Fritschi, L.; Gerkema, M.; Gordijn, M.; Merrrow, M.; Rajaratnam, S.M.W.; Rock, D.; Sletten, T.L.; Warman, G.; Wulff, K.; Roenneberg, T.; Foster, R.G. |
| Title |
Chronotype and environmental light exposure in a student population |
Type |
Journal Article |
| Year |
2018 |
Publication |
Chronobiology International |
Abbreviated Journal  |
Chronobiol Int |
| Volume |
35 |
Issue |
10 |
Pages |
1365-1374 |
| Keywords |
Human Health |
| Abstract |
In humans and most other species, changes in the intensity and duration of light provide a critical set of signals for the synchronisation of the circadian system to the astronomical day. The timing of activity within the 24 h day defines an individual's chronotype, i.e. morning, intermediate or evening type. The aim of this study was to investigate the associations between environmental light exposure, due to geographical location, on the chronotype of university students. Over 6 000 university students from cities in the Northern Hemisphere (Oxford, Munich and Groningen) and Southern Hemisphere (Perth, Melbourne and Auckland) completed the Munich ChronoType Questionnaire. In parallel, light measures (daily irradiance, timing of sunrise and sunset) were compiled from satellite or ground stations at each of these locations. Our data shows that later mid-sleep point on free days (corrected for oversleep on weekends MFSsc) is associated with (i) residing further from the equator, (ii) a later sunset, (iii) spending more time outside and (iv) waking from sleep significantly after sunrise. However, surprisingly, MSFsc did not correlate with daily light intensity at the different geographical locations. Although these findings appear to contradict earlier studies suggesting that in the wider population increased light exposure is associated with an earlier chronotype, our findings are derived exclusively from a student population aged between 17 and 26 years. We therefore suggest that the age and occupation of our population increase the likelihood that these individuals will experience relatively little light exposure in the morning whilst encountering more light exposure later in the day, when light has a delaying effect upon the circadian system. |
| Address |
a Sleep and Circadian Neuroscience Institute (SCNi), Nuffield Department of Clinical Neurosciences , University of Oxford , Oxford , UK |
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English |
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| ISSN |
0742-0528 |
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| Notes |
PMID:29913073 |
Approved |
no |
| Call Number |
GFZ @ kyba @ |
Serial |
1962 |
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| Author |
Ostrin, L.A. |
| Title |
Ocular and systemic melatonin and the influence of light exposure |
Type |
Journal Article |
| Year |
2018 |
Publication |
Clinical & Experimental Optometry |
Abbreviated Journal |
Clin Exp Optom |
| Volume |
in press |
Issue |
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Pages |
in press |
| Keywords |
Vision; Review; Human Health |
| Abstract |
Melatonin is a neurohormone known to modulate a wide range of circadian functions, including sleep. The synthesis and release of melatonin from the pineal gland is heavily influenced by light stimulation of the retina, particularly through the intrinsically photosensitive retinal ganglion cells. Melatonin is also synthesised within the eye, although to a much lesser extent than in the pineal gland. Melatonin acts directly on ocular structures to mediate a variety of diurnal rhythms and physiological processes within the eye. The interactions between melatonin, the eye, and visual function have been the subject of a considerable body of recent research. This review is intended to provide a broad introduction for eye-care practitioners and researchers to the topic of melatonin and the eye. The first half of the review describes the anatomy and physiology of melatonin production: how visual inputs affect the pineal production of melatonin; how melatonin is involved in a variety of diurnal rhythms within the eye, including photoreceptor disc shedding, neuronal sensitivity, and intraocular pressure control; and melatonin production and physiological roles in retina, ciliary body, lens and cornea. The second half of the review describes clinical implications of light/melatonin interactions. These include light exposure and photoreceptor contributions in melatonin suppression, leading to consideration of how blue blockers, cataract, and light therapy might affect sleep and mood in patients. Additionally, the interactions between melatonin, sleep and refractive error development are discussed. A better understanding of environmental factors that affect melatonin and subsequent effects on physiological processes will allow clinicians to develop treatments and recommend modifiable behaviours to improve sleep, increase daytime alertness, and regulate ocular and systemic processes related to melatonin. |
| Address |
University of Houston College of Optometry, Houston, Texas, USA |
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English |
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| ISSN |
0816-4622 |
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| Notes |
PMID:30074278 |
Approved |
no |
| Call Number |
GFZ @ kyba @ |
Serial |
1986 |
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| Author |
Carta, M.G.; Preti, A.; Akiskal, H.S. |
| Title |
Coping with the New Era: Noise and Light Pollution, Hperactivity and Steroid Hormones. Towards an Evolutionary View of Bipolar Disorders |
Type |
Journal Article |
| Year |
2018 |
Publication |
Clinical Practice and Epidemiology in Mental Health : CP & EMH |
Abbreviated Journal |
Clin Pract Epidemiol Ment Health |
| Volume |
14 |
Issue |
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Pages |
33-36 |
| Keywords |
Human Health |
| Abstract |
Human population is increasing in immense cities with millions of inhabitants, in which life is expected to run 24 hours a day for seven days a week (24/7). Noise and light pollution are the most reported consequences, with a profound impact on sleep patterns and circadian biorhythms. Disruption of sleep and biorhythms has severe consequences on many metabolic pathways. Suppression of melatonin incretion at night and the subsequent effect on DNA methylation may increase the risk of prostate and breast cancer. A negative impact of light pollution on neurosteroids may also affect mood. People who carry the genetic risk of bipolar disorder may be at greater risk of full-blown bipolar disorder because of the impact of noise and light pollution on sleep patterns and circadian biorhythms. However, living in cities may also offers opportunities and might be selective for people with hyperthymic temperament, who may find themselves advantaged by increased energy prompted by increased stimulation produced by life in big cities. This might result in the spreading of the genetic risk of bipolar disorder in the coming decades. In this perspective the burden of poor quality of life, increased disability adjusted life years and premature mortality due to the increases of mood disorders is the negative side of a phenomenon that in its globality also shows adaptive aspects. The new lifestyle also influences those who adapt and show behaviors, reactions and responses that might resemble the disorder, but are on the adaptive side. |
| Address |
University of California at San Diego USA |
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English |
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Series Issue |
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Edition |
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| ISSN |
1745-0179 |
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| Notes |
PMID:29541149; PMCID:PMC5838624 |
Approved |
no |
| Call Number |
GFZ @ kyba @ |
Serial |
1823 |
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| Author |
Lowden, A.; Lemos, N.; Gonçalves, B.; Öztürk, G.; Louzada, F.; Pedrazzoli, M.; Moreno, C. |
| Title |
Delayed Sleep in Winter Related to Natural Daylight Exposure among Arctic Day Workers |
Type |
Journal Article |
| Year |
2018 |
Publication |
Clocks & Sleep |
Abbreviated Journal |
Clocks & Sleep |
| Volume |
1 |
Issue |
1 |
Pages |
105-116 |
| Keywords |
Human Health |
| Abstract |
Natural daylight exposures in arctic regions vary substantially across seasons. Negative consequences have been observed in self-reports of sleep and daytime functions during the winter but have rarely been studied in detail. The focus of the present study set out to investigate sleep seasonality among indoor workers using objective and subjective measures. Sleep seasonality among daytime office workers (n = 32) in Kiruna (Sweden, 67.86° N, 20.23° E) was studied by comparing the same group of workers in a winter and summer week, including work and days off at the weekend, using actigraphs (motion loggers) and subjective ratings of alertness and mood. Actigraph analyses showed delayed sleep onset of 39 min in winter compared to the corresponding summer week (p < 0.0001) and shorter weekly sleep duration by 12 min (p = 0.0154). A delay of mid-sleep was present in winter at workdays (25 min, p < 0.0001) and more strongly delayed during days off (46 min, p < 0.0001). Sleepiness levels were higher in winter compared to summer (p < 0.05). Increased morning light exposure was associated with earlier mid-sleep (p < 0.001), while increased evening light exposure was associated with delay (p < 0.01). This study confirms earlier work that suggests that lack of natural daylight delays the sleep/wake cycle in a group of indoor workers, despite having access to electric lighting. Photic stimuli resulted in a general advanced sleep/wake rhythm during summer and increased alertness levels. |
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Edition |
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| ISSN |
2624-5175 |
ISBN |
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| Notes |
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Approved |
no |
| Call Number |
GFZ @ kyba @ |
Serial |
2137 |
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| Author |
Liu, Q.; Manning, A.J.; Duston, J. |
| Title |
Light intensity and suppression of nocturnal plasma melatonin in Arctic charr (Salvelinus alpinus) |
Type |
Journal Article |
| Year |
2018 |
Publication |
Comparative Biochemistry and Physiology. Part A, Molecular & Integrative Physiology |
Abbreviated Journal |
Comp Biochem Physiol A Mol Integr Physiol |
| Volume |
in press |
Issue |
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Pages |
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| Keywords |
Animals |
| Abstract |
The problem of early sexual maturation among farmed Arctic charr and other salmonids can be effectively reduced by 24h light overwinter, provided it is bright enough to over-ride interference from the natural daylength cycle. To determine the threshold light intensity to suppress the nocturnal elevation of plasma melatonin, three groups of individually tagged fish (n=26-28/group ca. 1040g) were reared on 12h light: 12h dark (LD 12:12) and subjected to nighttime light intensities of either 50-65, 0.1-0.3 or 0 (control) lux for five months (November to April). Daytime light intensity was 720-750lx. Diel plasma melatonin profiles in both November and April were similar; mean daytime levels ranged from 20 to 100pg/ml, and nighttime levels were inversely proportional to light intensity. In the control group at 0lx, plasma melatonin increased about four-fold after lights-off, ranging between 320 and 430pg/ml. Nighttime light intensity of 0.1-0.3lx halved plasma melatonin levels to 140-220pg/ml, and 50-65lx further reduced the levels to one quarter of the control group, 68-108pg/ml. Among the lit groups, daytime plasma melatonin levels were about 20-30pg/ml, significantly lower than the nocturnal levels suggesting the diel hormonal rhythm was not completely abolished. Fish grew steadily from about 1100g to 1600g between November and April, independent of light intensity (P=.67). Overall, the study demonstrated the sensitivity of pineal melatonin hormone to different light intensities in Arctic charr. |
| Address |
Department of Animal Science and Aquaculture, Dalhousie University, Agricultural Campus, Truro, NS B2N 5E3, Canada |
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English |
Summary Language |
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Edition |
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| ISSN |
1095-6433 |
ISBN |
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| Notes |
PMID:30471350 |
Approved |
no |
| Call Number |
GFZ @ kyba @ |
Serial |
2111 |
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