|   | 
Details
   web
Records
Author Stevens, R.G.
Title Artificial lighting in the industrialized world: circadian disruption and breast cancer Type Journal Article
Year 2006 Publication Cancer Causes & Control : CCC Abbreviated Journal (up) Cancer Causes Control
Volume 17 Issue 4 Pages 501-507
Keywords Human Health; Alcohol Drinking/adverse effects; Animals; Breast Neoplasms/*etiology; Chronobiology Disorders/*etiology/physiopathology; Circadian Rhythm; Developing Countries; Female; Humans; Lighting/*adverse effects; Melatonin/metabolism; Risk Factors; Suprachiasmatic Nucleus/physiopathology
Abstract Breast cancer risk is high in industrialized societies, and increases as developing countries become more Westernized. The reasons are poorly understood. One possibility is circadian disruption from aspects of modern life, in particular the increasing use of electric power to light the night, and provide a sun-free environment during the day inside buildings. Circadian disruption could lead to alterations in melatonin production and in changing the molecular time of the circadian clock in the suprachiasmatic nuclei (SCN). There is evidence in humans that the endogenous melatonin rhythm is stronger for persons in a bright-day environment than in a dim-day environment; and the light intensity necessary to suppress melatonin at night continues to decline as new experiments are done. Melatonin suppression can increase breast tumorigenesis in experimental animals, and altering the endogenous clock mechanism may have downstream effects on cell cycle regulatory genes pertinent to breast tissue development and susceptibility. Therefore, maintenance of a solar day-aligned circadian rhythm in endogenous melatonin and in clock gene expression by exposure to a bright day and a dark night, may be a worthy goal. However, exogenous administration of melatonin in an attempt to achieve this goal may have an untoward effect given that pharmacologic dosing with melatonin has been shown to phase shift humans depending on the time of day it's given. Exogenous melatonin may therefore contribute to circadian disruption rather than alleviate it.
Address University of Connecticut Health Center, Farmington, CT 06030-6325, USA. bugs@neuron.uchc.edu
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 0957-5243 ISBN Medium
Area Expedition Conference
Notes PMID:16596303 Approved no
Call Number LoNNe @ kagoburian @ Serial 818
Permanent link to this record
 

 
Author Peplonska, B.; Bukowska, A.; Sobala, W.; Reszka, E.; Gromadzinska, J.; Wasowicz, W.; Lie, J.A.; Kjuus, H.; Ursin, G.
Title Rotating night shift work and mammographic density Type Journal Article
Year 2012 Publication Cancer Epidemiology, Biomarkers & Prevention : a Publication of the American Association for Cancer Research, Cosponsored by the American Society of Preventive Oncology Abbreviated Journal (up) Cancer Epidemiol Biomarkers Prev
Volume 21 Issue 7 Pages 1028-1037
Keywords Adult; Breast/*pathology; Breast Neoplasms/*etiology/*pathology; Circadian Rhythm/*physiology; Cross-Sectional Studies; Female; Humans; Melatonin/urine; Middle Aged; *Midwifery; *Nursing Staff; Questionnaires; Risk Factors; *Work Schedule Tolerance; oncogenesis
Abstract BACKGROUND: An increased risk of breast cancer has been observed in night shift workers. Exposure to artificial light at night and disruption of the endogenous circadian rhythm with suppression of the melatonin synthesis have been suggested mechanisms. We investigated the hypothesis that rotating night shift work is associated with mammographic density. METHODS: We conducted a cross-sectional study on the association between rotating night shift work characteristics, 6-sulfatoxymelatonin (MT6s) creatinine adjusted in a spot morning urine sample, and a computer-assisted measure of mammographic density in 640 nurses and midwives ages 40 to 60 years. The associations were evaluated using regression models adjusted for age, body mass index, menopausal status, age at menopause, age at menarche, smoking, and the calendar season of the year when mammography was conducted. RESULTS: The adjusted means of percentage of mammographic density and absolute density were slightly higher among women working rotating night shifts but not statistically significant [percentage of mammographic density = 23.6%, 95% confidence interval (CI), 21.9%-25.4% vs. 22.5%, 95% CI, 20.8%-24.3%; absolute density = 23.9 cm(2), 95% CI, 21.4-26.4 cm(2) vs. 21.8 cm(2), 95% CI, 19.4-24.3 cm(2) in rotating night shift and day shift nurses, respectively). There were no significant associations between the current or cumulative rotating night shift work exposure metrics and mammographic density. No association was observed between morning MT6s and mammographic density. CONCLUSIONS: The hypothesis on the link between rotating night shift work, melatonin synthesis disruption, and mammographic density is not supported by the results of the present study. IMPACT: It is unlikely that the development of breast cancer in nurses working rotating night shifts is mediated by an increase in mammographic density.
Address Department of Environmental Epidemiology, Nofer Institute of Occupational Medicine, Lodz, Poland. beatap@imp.lodz.pl
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 1055-9965 ISBN Medium
Area Expedition Conference
Notes PMID:22539602 Approved no
Call Number IDA @ john @ Serial 159
Permanent link to this record
 

 
Author Blask, D.E.; Brainard, G.C.; Dauchy, R.T.; Hanifin, J.P.; Davidson, L.K.; Krause, J.A.; Sauer, L.A.; Rivera-Bermudez, M.A.; Dubocovich, M.L.; Jasser, S.A.; Lynch, D.T.; Rollag, M.D.; Zalatan, F.
Title Melatonin-depleted blood from premenopausal women exposed to light at night stimulates growth of human breast cancer xenografts in nude rats Type Journal Article
Year 2005 Publication Cancer Research Abbreviated Journal (up) Cancer Res
Volume 65 Issue 23 Pages 11174-11184
Keywords Human Health; Animals; Breast Neoplasms/*blood/genetics/pathology; Cell Growth Processes/physiology; Circadian Rhythm/*physiology; Female; Humans; Light; Liver Neoplasms, Experimental/metabolism; Male; Melatonin/blood/*deficiency; Premenopause/blood; RNA, Messenger/biosynthesis/genetics; Rats; Rats, Nude; Receptors, Melatonin/biosynthesis/genetics; Transplantation, Heterologous
Abstract The increased breast cancer risk in female night shift workers has been postulated to result from the suppression of pineal melatonin production by exposure to light at night. Exposure of rats bearing rat hepatomas or human breast cancer xenografts to increasing intensities of white fluorescent light during each 12-hour dark phase (0-345 microW/cm2) resulted in a dose-dependent suppression of nocturnal melatonin blood levels and a stimulation of tumor growth and linoleic acid uptake/metabolism to the mitogenic molecule 13-hydroxyoctadecadienoic acid. Venous blood samples were collected from healthy, premenopausal female volunteers during either the daytime, nighttime, or nighttime following 90 minutes of ocular bright, white fluorescent light exposure at 580 microW/cm2 (i.e., 2,800 lx). Compared with tumors perfused with daytime-collected melatonin-deficient blood, human breast cancer xenografts and rat hepatomas perfused in situ, with nocturnal, physiologically melatonin-rich blood collected during the night, exhibited markedly suppressed proliferative activity and linoleic acid uptake/metabolism. Tumors perfused with melatonin-deficient blood collected following ocular exposure to light at night exhibited the daytime pattern of high tumor proliferative activity. These results are the first to show that the tumor growth response to exposure to light during darkness is intensity dependent and that the human nocturnal, circadian melatonin signal not only inhibits human breast cancer growth but that this effect is extinguished by short-term ocular exposure to bright, white light at night. These mechanistic studies are the first to provide a rational biological explanation for the increased breast cancer risk in female night shift workers.
Address Laboratory of Chrono-Neuroendocrine Oncology, Bassett Research Institute, The Mary Imogene Bassett Hospital, Cooperstown, New York 13326, USA. david.blask@bassett.org
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 0008-5472 ISBN Medium
Area Expedition Conference
Notes PMID:16322268 Approved no
Call Number LoNNe @ kagoburian @ Serial 721
Permanent link to this record
 

 
Author Boivin, D.B.; Boudreau, P.; James, F.O.; Kin, N.M.K.N.Y.
Title Photic resetting in night-shift work: impact on nurses' sleep Type Journal Article
Year 2012 Publication Chronobiology International Abbreviated Journal (up) Chronobiol Int
Volume 29 Issue 5 Pages 619-628
Keywords Adaptation, Physiological; Adult; *Circadian Rhythm; *Darkness; Female; Humans; *Light; Male; Melatonin/metabolism; Middle Aged; *Nurses; Sleep/*physiology; Work Schedule Tolerance/*physiology
Abstract The objective of this study was to quantify daytime sleep in night-shift workers with and without an intervention designed to recover the normal relationship between the endogenous circadian pacemaker and the sleep/wake cycle. Workers of the treatment group received intermittent exposure to full-spectrum bright light during night shifts and wore dark goggles during the morning commute home. All workers maintained stable 8-h daytime sleep/darkness schedules. The authors found that workers of the treatment group had daytime sleep episodes that lasted 7.1 +/- .1 h (mean +/- SEM) versus 6.6 +/- .2 h for workers in the control group (p = .04). The increase in total sleep time co-occurred with a larger proportion of the melatonin secretory episode during daytime sleep in workers of the treatment group. The results of this study showed reestablishment of a phase angle that is comparable to that observed on a day-oriented schedule favors longer daytime sleep episodes in night-shift workers. (Author correspondence: diane.boivin@douglas.mcgill.ca ).
Address Centre for Study and Treatment of Circadian Rhythms, Douglas Mental Health University Institute, Department of Psychiatry, McGill University, Montreal, Quebec, Canada. diane.boivin@douglas.mcgill.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 0742-0528 ISBN Medium
Area Expedition Conference
Notes PMID:22621359 Approved no
Call Number IDA @ john @ Serial 144
Permanent link to this record
 

 
Author Lowden, A.; Akerstedt, T.
Title Assessment of a new dynamic light regimen in a nuclear power control room without windows on quickly rotating shiftworkers--effects on health, wakefulness, and circadian alignment: a pilot study Type Journal Article
Year 2012 Publication Chronobiology International Abbreviated Journal (up) Chronobiol Int
Volume 29 Issue 5 Pages 641-649
Keywords Adaptation, Physiological; Adult; *Circadian Rhythm; Darkness/adverse effects; *Environment, Controlled; Female; Humans; *Light; Male; Melatonin/metabolism; Middle Aged; Photic Stimulation; Pilot Projects; Saliva/chemistry; Sleep/*physiology; *Wakefulness; *Work Schedule Tolerance
Abstract The aim of the study was to test whether a new dynamic light regime would improve alertness, sleep, and adaptation to rotating shiftwork. The illumination level in a control room without windows at a nuclear power station was ~200 lux (straight-forward horizontal gaze) using a weak yellow light of 200 lux, 3000 K (Philips Master TLD 36 W 830). New lighting equipment was installed in one area of the control room above the positions of the reactor operators. The new lights were shielded from the control group by a distance of >6 m, and the other operators worked at desks turned away from the new light. The new lights were designed to give three different light exposures: (i) white/blue strong light of 745 lux, 6000 K; (ii) weak yellow light of 650 lux, 4000 K; and (iii) yellow moderate light of 700 lux, 4000 K. In a crossover design, the normal and new light exposures were given during a sequence of three night shifts, two free days, two morning shifts, and one afternoon shift (NNN + MMA), with 7 wks between sessions. The operators consisted of two groups; seven reactor operators from seven work teams were at one time exposed to the new equipment and 16 other operators were used as controls. The study was conducted during winter with reduced opportunities of daylight exposure during work, after night work, or before morning work. Operators wore actigraphs, filled in a sleep/wake diary, including ratings of sleepiness on the Karolinska Sleepiness Scale (KSS) every 2 h, and provided saliva samples for analysis of melatonin at work (every 2nd h during one night shift and first 3 h during one morning shift). Results from the wake/sleep diary showed the new light treatment increased alertness during the 2nd night shift (interaction group x light x time, p < .01). Time of waking was delayed in the light condition after the 3rd night shift (group x light, p < .05), but the amount of wake time during the sleep span increased after the 2nd night shift (p < .05), also showing a tendency to affect sleep efficiency (p < .10). Effects on circadian phase were difficult to establish given the small sample size and infrequent sampling of saliva melatonin. Nonetheless, it seems that appropriate dynamic light in rooms without windows during the dark Nordic season may promote alertness, sleep, and better adaptation to quickly rotating shiftwork.
Address Stress Research Institute, Stockholm University, Stockholm, Sweden. arne.lowden@stress.su.se
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 0742-0528 ISBN Medium
Area Expedition Conference
Notes PMID:22621361 Approved no
Call Number IDA @ john @ Serial 148
Permanent link to this record