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Author Obayashi, K.; Saeki, K.; Iwamoto, J.; Okamoto, N.; Tomioka, K.; Nezu, S.; Ikada, Y.; Kurumatani, N.
Title Exposure to light at night, nocturnal urinary melatonin excretion, and obesity/dyslipidemia in the elderly: a cross-sectional analysis of the HEIJO-KYO study Type Journal Article
Year 2013 Publication The Journal of Clinical Endocrinology and Metabolism Abbreviated Journal J Clin Endocrinol Metab
Volume 98 Issue 1 Pages (down) 337-344
Keywords *Aged; Aged, 80 and over; Case-Control Studies; *Circadian Rhythm/physiology; Cross-Sectional Studies; Dyslipidemias/complications/metabolism/*urine; Female; Humans; Japan; *Light; Male; Melatonin/secretion/*urine; Obesity/complications/metabolism/*urine; Photoperiod
Abstract CONTEXT: Obesity and exposure to light at night (LAN) have increased globally. Although LAN suppresses melatonin secretion and disturbs body mass regulation in experimental settings, its associations with melatonin secretion, obesity, and other metabolic consequences in uncontrolled home settings remain unclear. OBJECTIVE: The aim of this study was to determine the association of exposure to LAN in an uncontrolled home setting with melatonin secretion, obesity, dyslipidemia, and diabetes. DESIGN AND PARTICIPANTS: A cross-sectional study was performed in 528 elderly individuals (mean age, 72.8 yr). MEASURES: The intensity of LAN in the bedroom was measured at 1-min intervals during two consecutive nights, along with overnight urinary melatonin excretion and metabolic parameters. RESULTS: Compared with the Dim group (average <3 lux; n = 383), the LAN group (average >/=3 lux; n = 145) showed significantly higher body weight (adjusted mean, 58.8 vs. 56.6 kg; P = 0.01), body mass index (23.3 vs. 22.7 kg/m(2); P = 0.04), waist circumference (84.9 vs. 82.8 cm; P = 0.01), triglyceride levels (119.7 vs. 99.5 mg/dl; P < 0.01), and low-density lipoprotein cholesterol levels (128.6 vs. 122.2 mg/dl; P = 0.04), and showed significantly lower high-density lipoprotein cholesterol levels (57.4 vs. 61.3 mg/dl; P = 0.02). These associations were independent of numerous potential confounders, including urinary melatonin excretion. Furthermore, LAN exposure is associated with higher odds ratios (ORs) for obesity (body mass index: OR, 1.89; P = 0.02; abdominal: OR, 1.62; P = 0.04) and dyslipidemia (OR, 1.72; P = 0.02) independent of demographic and socioeconomic parameters. In contrast, urinary melatonin excretion and glucose parameters did not show significant differences between the two groups. CONCLUSIONS: Exposure to LAN in an uncontrolled home setting is associated with impaired obese and lipid parameters independent of nocturnal urinary melatonin excretion in elderly individuals. Moreover, LAN exposure is associated with higher ORs for obesity and dyslipidemia independent of demographic and socioeconomic parameters.
Address Department of Community Health and Epidemiology, Nara Medical University School of Medicine, 840 Shijocho, Kashiharashi, Nara, 634-8521, Japan. obayashi@naramed-u.ac.jp
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 0021-972X ISBN Medium
Area Expedition Conference
Notes PMID:23118419 Approved no
Call Number IDA @ john @ Serial 168
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Author Obayashi, K.; Saeki, K.; Iwamoto, J.; Ikada, Y.; Kurumatani, N.
Title Exposure to light at night and risk of depression in the elderly Type Journal Article
Year 2013 Publication Journal of Affective Disorders Abbreviated Journal J Affect Disord
Volume 151 Issue 1 Pages (down) 331-336
Keywords Aged; Circadian Rhythm; Cross-Sectional Studies; Depression/*etiology; Female; Humans; Light/*adverse effects; Male; Melatonin/urine; Psychiatric Status Rating Scales; Risk Factors; Circadian rhythm; Daytime light; Depression; Elderly; Light at night; Melatonin; Mental Health
Abstract BACKGROUND: Recent advances in understanding the fundamental links between chronobiology and depressive disorders have enabled exploring novel risk factors for depression in the field of biological rhythms. Increased exposure to light at night (LAN) is common in modern life, and LAN exposure is associated with circadian misalignment. However, whether LAN exposure in home settings is associated with depression remains unclear. METHODS: We measured the intensities of nighttime bedroom light and ambulatory daytime light along with overnight urinary melatonin excretion (UME) in 516 elderly individuals (mean age, 72.8). Depressive symptoms were assessed using the Geriatric Depression Scale. RESULTS: The median nighttime light intensity was 0.8lx (interquartile range, 0.2-3.3). The depressed group (n=101) revealed significantly higher prevalence of LAN exposure (average intensity, >/= 5 lx) compared with that of the nondepressed group (n=415) using a multivariate logistic regression model adjusted for daytime light exposure, insomnia, hypertension, sleep duration, and physical activity [adjusted odds ratio (OR): 1.89; 95% confidence interval (CI), 1.10-3.25; P=0.02]. Consistently, another parameter of LAN exposure (duration of intensity >/= 10 lx, >/= 30 min) was significantly more prevalent in the depressed than in the nondepressed group (adjusted OR: 1.71; 95% CI, 1.01-2.89; P=0.046). In contrast, UME was not significantly associated with depressive symptoms. LIMITATION: Cross-sectional analysis. CONCLUSION: These results suggested that LAN exposure in home settings is significantly associated with depressive symptoms in the general elderly population. The risk of depression may be reduced by keeping nighttime bedroom dark.
Address Department of Community Health and Epidemiology, Nara Medical University School of Medicine, Nara, Japan. obayashi@naramed-u.ac.jp
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 0165-0327 ISBN Medium
Area Expedition Conference
Notes PMID:23856285 Approved no
Call Number IDA @ john @ Serial 165
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Author Reiter, R.J.; Tan, D.X.; Korkmaz, A.; Rosales-Corral, S.A.
Title Melatonin and stable circadian rhythms optimize maternal, placental and fetal physiology Type Journal Article
Year 2014 Publication Human Reproduction Update Abbreviated Journal Hum Reprod Update
Volume 20 Issue 2 Pages (down) 293-307
Keywords Human Health; Animals; Antioxidants/physiology; Biological Clocks/physiology; Circadian Rhythm/*physiology; Female; Fetus/*physiology; Humans; Mammals; Melatonin/biosynthesis/*physiology; Mice; Oxidative Stress/physiology; Parturition/physiology; Placenta/metabolism/*physiology; Pre-Eclampsia/etiology/metabolism; Pregnancy; Uterus/metabolism; circadian rhythms; fetus; melatonin; placenta; pre-eclampsia
Abstract BACKGROUND: Research within the last decade has shown melatonin to have previously-unsuspected beneficial actions on the peripheral reproductive organs. Likewise, numerous investigations have documented that stable circadian rhythms are also helpful in maintaining reproductive health. The relationship of melatonin and circadian rhythmicity to maternal and fetal health is summarized in this review. METHODS: Databases were searched for the related published English literature up to 15 May 2013. The search terms used in various combinations included melatonin, circadian rhythms, biological clock, suprachiasmatic nucleus, ovary, pregnancy, uterus, placenta, fetus, pre-eclampsia, intrauterine growth restriction, ischemia-reperfusion, chronodisruption, antioxidants, oxidative stress and free radicals. The results of the studies uncovered are summarized herein. RESULTS: Both melatonin and circadian rhythms impact reproduction, especially during pregnancy. Melatonin is a multifaceted molecule with direct free radical scavenging and indirect antioxidant activities. Melatonin is produced in both the ovary and in the placenta where it protects against molecular mutilation and cellular dysfunction arising from oxidative/nitrosative stress. The placenta, in particular, is often a site of excessive free radical generation due to less than optimal adhesion to the uterine wall, which leads to either persistent hypoxia or intermittent hypoxia and reoxygenation, processes that cause massive free radical generation and organ dysfunction. This may contribute to pre-eclampsia and other disorders which often complicate pregnancy. Melatonin has ameliorated free radical damage to the placenta and to the fetus in experiments using non-human mammals. Likewise, the maintenance of a regular maternal light/dark and sleep/wake cycle is important to stabilize circadian rhythms generated by the maternal central circadian pacemaker, the suprachiasmatic nuclei. Optimal circadian rhythmicity in the mother is important since her circadian clock, either directly or indirectly via the melatonin rhythm, programs the developing master oscillator of the fetus. Experimental studies have shown that disturbed maternal circadian rhythms, referred to as chronodisruption, and perturbed melatonin cycles have negative consequences for the maturing fetal oscillators, which may lead to psychological and behavioral problems in the newborn. To optimize regular circadian rhythms and prevent disturbances of the melatonin cycle during pregnancy, shift work and bright light exposure at night should be avoided, especially during the last trimester of pregnancy. Finally, melatonin synergizes with oxytocin to promote delivery of the fetus. Since blood melatonin levels are normally highest during the dark period, the propensity of childbirth to occur at night may relate to the high levels of melatonin at this time which work in concert with oxytocin to enhance the strength of uterine contractions. CONCLUSIONS: A number of conclusions naturally evolve from the data summarized in this review: (i) melatonin, of both pineal and placental origin, has essential functions in fetal maturation and placenta/uterine homeostasis; (ii) circadian clock genes, which are components of all cells including those in the peripheral reproductive organs, have important roles in reproductive and organismal (fetal and maternal) physiology; (iii) due to the potent antioxidant actions of melatonin, coupled with its virtual absence of toxicity, this indoleamine may have utility in the treatment of pre-eclampsia, intrauterine growth restriction, placental and fetal ischemia/reperfusion, etc. (iv) the propensity for parturition to occur at night may relate to the synergism between the nocturnal increase in melatonin and oxytocin.
Address Department of Cellular and Structural Biology, University of Texas Health Science Center, San Antonio, TX, USA
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 1355-4786 ISBN Medium
Area Expedition Conference
Notes PMID:24132226 Approved no
Call Number LoNNe @ christopher.kyba @ Serial 504
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Author Smith, M.R.; Revell, V.L.; Eastman, C.I.
Title Phase advancing the human circadian clock with blue-enriched polychromatic light Type Journal Article
Year 2009 Publication Sleep Medicine Abbreviated Journal Sleep Med
Volume 10 Issue 3 Pages (down) 287-294
Keywords Adult; Circadian Rhythm/*radiation effects; Female; Humans; *Light; Lighting/*methods; Male; Melatonin/metabolism; Phototherapy/*methods; Sleep; Wakefulness; Young Adult; blue light; sleep
Abstract BACKGROUND: Previous studies have shown that the human circadian system is maximally sensitive to short-wavelength (blue) light. Whether this sensitivity can be utilized to increase the size of phase shifts using light boxes and protocols designed for practical settings is not known. We assessed whether bright polychromatic lamps enriched in the short-wavelength portion of the visible light spectrum could produce larger phase advances than standard bright white lamps. METHODS: Twenty-two healthy young adults received either a bright white or bright blue-enriched 2-h phase advancing light pulse upon awakening on each of four treatment days. On the first treatment day the light pulse began 8h after the dim light melatonin onset (DLMO), on average about 2h before baseline wake time. On each subsequent day, light treatment began 1h earlier than the previous day, and the sleep schedule was also advanced. RESULTS: Phase advances of the DLMO for the blue-enriched (92+/-78 min, n=12) and white groups (76+/-45 min, n=10) were not significantly different. CONCLUSION: Bright blue-enriched polychromatic light is no more effective than standard bright light therapy for phase advancing circadian rhythms at commonly used therapeutic light levels.
Address Biological Rhythms Research Laboratory, Rush University Medical Center, Suite 425, 1645 W. Jackson Boulevard, Chicago, IL 60612, USA
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 1389-9457 ISBN Medium
Area Expedition Conference
Notes PMID:18805055; PMCID:PMC2723863 Approved no
Call Number IDA @ john @ Serial 289
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Author Dickerman, B.; Liu, J.
Title Does current scientific evidence support a link between light at night and breast cancer among female night-shift nurses? Review of evidence and implications for occupational and environmental health nurses Type Journal Article
Year 2012 Publication Workplace Health & Safety Abbreviated Journal Workplace Health Saf
Volume 60 Issue 6 Pages (down) 273-81; quiz 282
Keywords Human Health; Breast Neoplasms/*epidemiology/nursing; Chronobiology Disorders/*epidemiology/nursing; Education, Nursing, Continuing; Environmental Health; Evidence-Based Nursing; Female; Humans; Light; Night Care/*statistics & numerical data; *Occupational Health Nursing; Risk Factors; *Work Schedule Tolerance
Abstract Breast cancer is increasingly prevalent in industrialized regions of the world, and exposure to light at night (LAN) has been proposed as a potential risk factor. Epidemiological observations have documented an increased breast cancer risk among female night-shift workers, and strong experimental evidence for this relationship has also been found in rodent models. Indirect support for the LAN hypothesis comes from studies involving blind women, sleep duration, bedroom light levels, and community nighttime light levels. This article reviews the literature, discusses possible mechanisms of action, and provides recommendations for occupational health nursing research, practice, and education. Research is needed to further explore the relationship between exposure to LAN and breast cancer risk and elucidate the mechanisms underlying this relationship before interventions can be designed for prevention and mitigation of breast cancer.
Address MultiCare Good Samaritan Hospital, Puyallup, WA, USA. barbra.dickerman@gmail.com
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 2165-0799 ISBN Medium
Area Expedition Conference
Notes PMID:22658734 Approved no
Call Number LoNNe @ christopher.kyba @ Serial 512
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