Rotating-shift nurses after a day off: Peripheral clock gene expression, urinary melatonin, and serum 17-β-estradiol levels

Scandinavian Journal of Work, Environment and Health

Volumn 40, Issue 3, 2014, Pages 295-304

  Bracci, Massimo ^a   Manzella, Nicola ^a   Copertaro, Alfredo ^b   Staffolani, Sara ^a   Barbaresi, I Mariella ^a   Strafella, Elisabetta ^b   Copertaro, Benedetta ^b   Rapisarda, Venerando ^c   Valentino, Matteo ^a   Santarelli, Lory ^a  

^a UNIVERSITÀ POLITECNICA DELLE MARCHE   (Italy)

^b Loreto Hospital   (Italy)

^c UNIVERSITY OF CATANIA   (Italy)

Author keywords

6 sulfatoxymelatonin; aMT6s; Breast cancer; Chronotype; Circadian rhythm; Night work; Shift work; Shift worker; Work schedule tolerance

Indexed keywords

ESTRADIOL; MELATONIN; TRANSCRIPTION FACTOR CLOCK;

ADULT; BLOOD; CROSS-SECTIONAL STUDY; FEMALE; GENETICS; HUMAN; MALE; MIDDLE AGED; NURSING STAFF; PERSONNEL MANAGEMENT; URINE; WORK SCHEDULE;

ADULT; CLOCK PROTEINS; CROSS-SECTIONAL STUDIES; ESTRADIOL; FEMALE; HUMANS; MALE; MELATONIN; MIDDLE AGED; NURSING STAFF, HOSPITAL; PERSONNEL STAFFING AND SCHEDULING; WORK SCHEDULE TOLERANCE;

EID: 84899843944     PISSN: 03553140     EISSN: 1795990X     Source Type: Journal    
DOI: 10.5271/sjweh.3414     Document Type: Article

References (94)

1. Costa G, Haus E, Stevens R. Shift work and cancer-considerations on rationale, mechanisms, and epidemiology. Scand J Work Environ Health. 2010;36:163-179. http://dx.doi.org/10.5271/sjweh.2899
2. Stevens RG. Circadian disruption and breast cancer: from melatonin to clock genes. Epidemiology. 2005;16: 254-258. http://dx.doi.org/10.1097/01.ede.0000152525.21924.54
3. Di Milia L, Waage S, Pallesen S, Bjorvatn B. Shift work disorder in a random population sample--prevalence and comorbidities. PLoS One. 2013. http://dx.doi.org/10.1371/journal.pone.0055306
4. Copertaro A, Bracci M, Barbaresi M, Santarelli L. Assessment of cardiovascular risk in shift healthcare workers. Eur J Cardiovasc Prev Rehabil. 2008;15:224-229. http://dx.doi.org/10.1097/HJR.0b013e3282f364c0
5. Flo E, Pallesen S, Magerøy N, Moen BE, Grønli J, Hilde Nordhus I, et al. Shift work disorder in nurses--assessment, prevalence and related health problems. PLoS One 2012. http://dx.doi.org/10.1371/journal.pone.0033981
6. International Agency for Research on Cancer (IARC). Painting, firefighting, and shiftwork. Lyon: IARC; 2010. IARC Monographs on the evaluation of the carcinogenic risks of chemicals to humans, vol 98.
7. Schernhammer ES, Laden F, Speizer FE, Willett WC, Hunter DJ, Kawachi I, et al. Rotating night shifts and risk of breast cancer in women participating in the nurses' health study. J Natl Cancer Inst. 2001;93:1563-1568. http://dx.doi.org/10.1093/jnci/93.20.1563
8. Davis S, Mirick DK, Stevens RG. Night shift work, light at night, and risk of breast cancer. J Natl Cancer Inst. 2001;93:1557-1562. http://dx.doi.org/10.1093/jnci/93.20.1557
9. Hansen J. Increased breast cancer risk among women who work predominantly at night. Epidemiology 2001;12:74-77. http://dx.doi.org/10.1097/00001648-200101000-00013
10. Schernhammer ES, Kroenke CH, Laden F, Hankinson SE. Night work and risk of breast cancer. Epidemiology 2006;17:108-111. http://dx.doi.org/10.1097/01.ede.0000190539.03500.c1
11. Hansen J, Lassen CF. Nested case-control study of night shift work and breast cancer risk among women in the Danish military. Occup Environ Med. 2012;69:551-556. http://dx.doi.org/10.1136/oemed-2011-100240
12. Grundy A, Richardson H, Burstyn I, Lohrisch C, Sengupta SK, Lai AS, et al. Increased risk of breast cancer associated with long-term shift work in Canada. Occup Environ Med. 2013;70:831-838. http://dx.doi.org/10.1136/oemed-2013-101482
13. Wang F, Yeung KL, Chan WC, Kwok CC, Leung SL, Wu C, et al. A meta-analysis on dose-response relationship between night shift work and the risk of breast cancer. Ann Oncol. 2013;24:2724-2732. http://dx.doi.org/10.1093/annonc/mdt283
14. Pesch B, Harth V, Rabstein S, Baisch C, Schiffermann M, Pallapies D, et al. Night work and breast cancer-results from the German GENICA study. Scand J Work Environ Health. 2010;36:134-141. http://dx.doi.org/10.5271/sjweh.2890
15. Rabstein S, Harth V, Pesch B, Pallapies D, Lotz A, Justenhoven C, et al. Night work and breast cancer estrogen receptor status--results from the German GENICA study. Scand J Work Environ Health. 2013;39:448-455. http://dx.doi.org/10.5271/sjweh.3360
16. Knutsson A, Alfredsson L, Karlsson B, Akerstedt T, Fransson EI, Westerholm P, et al. Breast cancer among shift workers: results of the WOLF longitudinal cohort study. Scand J Work Environ Health. 2013;39:170-177. http://dx.doi.org/10.5271/sjweh.3323
17. Bonde JP, Hansen J, Kolstad HA, Mikkelsen S, Olsen JH, Blask DE, et al. Work at night and breast cancer--report on evidence-based options for preventive actions. Scand J Work Environ Health. 2012;38:380-390. http://dx.doi.org/10.5271/sjweh.3282
18. Dibner C, Schibler U, Albrecht U. The mammalian circadian timing system: organization and coordination of central and peripheral clocks. Annu Rev Physiol. 2010;72:517-549. http://dx.doi.org/10.1146/annurev-physiol-021909-135821
19. Slat E, Freeman GM Jr, Herzog ED. The clock in the brain: neurons, glia, andnetworks in daily rhythms. Handb Exp Pharmacol. 2013;217:105-123. http://dx.doi.org/10.1007/978-3-642-25950-0_5.
20. Brown SA, Azzi A. Peripheral circadian oscillators in mammals. Handb Exp Pharmacol. 2013;217:45-66. http://dx.doi.org/10.1007/978-3-642-25950-0_3
21. Reppert SM, Weaver DR. Coordination of circadian timing in mammals. Nature. 2002;418: 935-941. http://dx.doi.org/10.1038/nature00965
22. Lowrey PL, Takahashi JS. Mammalian circadian biology: elucidating genome-wide levels of temporal organization. Annu Rev Genomics Hum Genet. 2004;5:407-441. http://dx.doi.org/10.1146/annurev.genom.5.061903.175925
23. Rana S, Mahmood S. Circadian rhythm and its role in malignancy. J Circadian Rhythms. 2010;8:3. http://dx.doi.org/10.1186/1740-3391-8-3
24. Gómez-Abellán P, Hernández-Morante JJ, Luján JA, Madrid JA, Garaulet M. Clock genes are implicated in the human metabolic syndrome. Int J Obes (Lond). 2008;32:121-128. http://dx.doi.org/10.1038/sj.ijo.0803689
25. Ando H, Ushijima K, Kumazaki M, Eto T, Takamura T, Irie S, et al. Associations of metabolic parameters and ethanol consumption with messenger RNA expression of clock genes in healthy men. Chronobiol Int. 2010; 27:194-203. http://dx.doi.org/10.3109/07420520903398617
26. Woon PY, Kaisaki PJ, Bragança J, Bihoreau MT, Levy JC, Farrall M et al. Aryl hydrocarbon receptor nuclear translocator-like (BMAL1) is associated with susceptibility to hypertension and type 2 diabetes. Proc Natl Acad Sci U S A. 2007; 104:14412-14417. http://dx.doi.org/10.1073/pnas.0703247104
27. Stevens RG. Artificial lighting in the industrialized world: circadian disruption and breast cancer. Cancer Causes Control. 2006;17:501-507. http://dx.doi.org/10.1007/s10552-005-9001-x
28. Hida A, Kitamura S, Ohsawa Y, Enomoto M, Katayose Y, Motomura Y, et al. In vitro circadian period is associated with circadian/sleep preference. Sci Rep. 2013;3:2074. http://dx.doi.org/10.1038/srep02074
29. Osland TM, Bjorvatn BR, Steen VM, Pallesen Sl. Association study of a variable-number tandem repeat polymorphism in the clock gene PERIOD3 and chronotype in Norwegian university students. Chronobiol Int. 2011;28:764-70. http://dx.doi.org/10.3109/07420528.2011.607375
30. Brown SA, Kunz D, Dumas A, Westermark PO, Vanselow K, Tilmann-Wahnschaffe A, Herzel H, Kramer A. Molecular insights into human daily behavior. Proc Natl Acad Sci U S A. 2008;105:1602-1607. http://dx.doi.org/10.1073/pnas.0707772105
31. Sack RL, Auckley D, Auger RR, Carskadon MA, Wright KP Jr, Vitiello MV, et al. Circadian rhythm sleep disorders: part I, basic principles, shift work and jet lag disorders. An American Academy of Sleep Medicine review. Sleep. 2007;30:1460-1483.
32. Gamble KL, Motsinger-Reif AA, Hida A, Borsetti HM, Servick SV, Ciarleglio CM, et al. Shift work in nurses: contribution of phenotypes and genotypes to adaptation. PLoS One. 2011. http://dx.doi.org/10.1371/journal.pone.0018395
33. Hansen J, Lassen CF. Nested case-control study of night shift work and breast cancer risk among women in the Danish military. Occup Environ Med. 2012;69:551-556. http://dx.doi.org/10.1136/oemed-2011-100240
34. Schernhammer ES, Schulmeister K. Melatonin and cancer risk: does light at night compromise physiologic cancer protection by lowering serum melatonin levels? Br J Cancer. 2004;90: 941-943. http://dx.doi.org/10.1038/sj.bjc.6601626
35. Stevens RG, Blask DE, Brainard GC, Hansen J, Lockley SW, Provencio I, et al. Meeting report: the role of environmental lighting and circadian disruption in cancer and other diseases. Environ Health Perspect. 2007;115:1357-62. http://dx.doi.org/10.1289/ehp.10200
36. Mirick DK, Davis S. Melatonin as a biomarker of circadian dysregulation. Cancer Epidemiol Biomarkers Prev. 2008;17:3306-3313. http://dx.doi.org/10.1158/1055-9965.EPI-08-0605
37. Cos S, González A, Martínez-Campa C, Mediavilla MD, Alonso-González C, Sanchez-Barceló EJ. Melatonin as a selective estrogen enzyme modulator. Curr Cancer Drug Targets. 2008;8: 691-702. http://dx.doi.org/10.2174/156800908786733469
38. Nelson R. Steroidal oestrogens added to list of known human carcinogens. Lancet. 2002;360: 2053. http://dx.doi.org/10.1016/S0140-6736(02)12045-9
39. Stevens RG. Working against our endogenous circadian clock: Breast cancer and electric lighting in the modern world. Mutat Res. 2009; 680:106-108. http://dx.doi.org/10.1016/j.mrgentox.2009.08.004
40. Ni Ji BT, Gao YT, Shu XO, Yang G, Yu K, Xue SZ, et al. Nightshift work job exposure matrices and urinary 6-sulfatoxymelatonin levels among healthy Chinese women. Scand J Work Environ Health. 2012;38:553-559. http://dx.doi.org/10.5271/sjweh.3322
41. Peplonska B, Bukowska A, Gromadzinska J, Sobala W, Reszka E, Lie JA, et al. Night shift work characteristics and 6-sulfatoxymelatonin (MT6s) in rotating night shift nurses and midwives. Occup Environ Med. 2012;69:339-346. http://dx.doi.org/10.1136/oemed-2011-100273
42. Davis S, Mirick DK, Chen C, Stanczyk FZ. Night shift work and hormone levels in women. Cancer Epidemiol Biomarkers Prev; 2012;21:609-618. http://dx.doi.org/10.1158/1055-9965.EPI-11-1128
43. Marie Hansen A, Helene Garde A, Hansen J. Diurnal urinary 6-sulfatoxymelatonin levels among healthy Danish nurses during work and leisure time. Chronobiol Int. 2006;23:1203-1215 http://dx.doi.org/10.1080/07420520601100955
44. Grundy A, Tranmer J, Richardson H, Graham CH, Aronson KJ. The influence of light at night exposure on melatonin levels among Canadian rotating shift nurses. Cancer Epidemiol Biomarkers Prev. 2011;20:2404-2412. http://dx.doi.org/10.1158/1055-9965.EPI-11-0427
45. Yamauchi H. Effects of night work on urinary excretion rates of 6sulfatoxymelatonin, norepinephrine and estriol in pregnant women. Ind Health. 2004;42:268-276. http://dx.doi.org/10.2486/indhealth.42.268
46. Schernhammer ES, Rosner B, Willett WC, Laden F, Colditz GA, Hankinson SE. Epidemiology of urinary melatonin in women and its relation to other hormones and night work. Cancer Epidemiol Biomarkers Prev. 2004;13: 936-943.
47. Davis S, Mirick DK, Chen C, Stanczyk FZ. Night shift work and hormone levels in women. Cancer Epidemiol Biomarkers Prev; 2012;21:609-618. http://dx.doi.org/10.1158/1055-9965.EPI-11-1128
48. Marie Hansen A, Helene Garde A, Hansen J. Diurnal urinary 6-sulfatoxymelatonin levels among healthy Danish nurses during work and leisure time. Chronobiol Int. 2006;23:1203-1215. http://dx.doi.org/10.1080/07420520601100955
49. Grundy A, Tranmer J, Richardson H, Graham CH, Aronson KJ. The influence of light at night exposure on melatonin levels among Canadian rotating shift nurses. Cancer Epidemiol Biomarkers Prev. 2011;20:2404-2412. http://dx.doi.org/10.1158/1055-9965.EPI-11-0427
50. Schernhammer ES, Kroenke CH, Dowsett M, Folkerd E, Hankinson SE. Urinary 6-sulfatoxymelatonin levels and their correlations with lifestyle factors and steroid hormone levels. J Pineal Res. 2006;40:116-124. http://dx.doi.org/10.1111/j.1600-079X.2005.00285.x
51. Nagata C, Nagao Y, Yamamoto S, Shibuya C, Kashiki Y, Shimizu H. Light exposure at night, urinary 6-sulfatoxymelatonin, and serum estrogens and androgens in postmenopausal Japanese women. Cancer Epidemiol Biomarkers Prev. 2008;17:1418-1423. http://dx.doi.org/10.1158/1055-9965.EPI-07-0656
52. Small CM, Marcus M, Sherman SL, Sullivan AK, Manatunga AK, Feigelson HS. CYP17 genotype predicts serum hormone levels among pre-menopausal women. Hum Reprod. 2005;20:2162-2167. http://dx.doi.org/10.1093/humrep/dei054
53. Eliassen AH, Missmer SA, Tworoger SS, Spiegelman D, Barbieri RL, Dowsett M, et al. Endogenous steroid hormone concentrations and risk of breast cancer among premenopausal women. J Natl Cancer Inst. 2006;98:1406-1415. http://dx.doi.org/10.1093/jnci/djj376
54. Buysse DJ, Reynolds CF 3rd, Monk TH, Berman SR, Kupfer DJ. The Pittsburgh Sleep Quality Index: a new instrument for psychiatric practice and research. Psychiatry Res. 1989;28:193-213. http://dx.doi.org/10.1016/0165-1781(89)90047-4
55. Horne JA, Ostberg O. A self-assessment questionnaire to determine morningness eveningness in human circadian rhythms. Int J Chronobiol. 1976;4:97-110.
56. Taillard J, Philip P, Chastang JF, Bioulac B. Validation of Horne and Ostberg morningness-eveningness questionnaire in a middle-aged population of French workers. J Biol Rhythms. 2004;19:76-86. http://dx.doi.org/10.1177/0748730403259849
57. Bajaj A, Rosner B, Lockley SW, Schernhammer ES. Validation of a light questionnaire with real-life photopic illuminance measurements: the Harvard Light Exposure Assessment questionnaire. Cancer Epidemiol Biomarkers Prev. 2011;20:1341-9. http://dx.doi.org/10.1158/1055-9965.EPI-11-0204
58. Chung MH, Chang FM, Yang CC, Kuo TB, Hsu N. Sleep quality and morningness-eveningness of shift nurses. J Clin Nurs. 2009;18:279-84. http://dx.doi.org/10.1111/j.1365-2702.2007.02160.x
59. Yazdi Z, Sadeghniiat-Haghighi K, Javadi AR, Rikhtegar G. Sleep quality and insomnia in nurses with different circadian chronotypes: Morningness and eveningness orientation. Work. 2013; Epub ahead of print.
60. Hsing AW, Meyer TE, Niwa S, Quraishi SM, Chu LW. Measuring serum melatonin in epidemiologic studies. Cancer Epidemiol Biomarkers Prev. 2010;19:932-7. http://dx.doi.org/10.1158/1055-9965.EPI-10-0004
61. Graham C, Cook MR, Kavet R, Sastre A, Smith DK. Prediction of nocturnal plasma melatonin from morning urinary measures. J Pineal Res. 1998 May;24:230-8. http://dx.doi.org/10.1111/j.1600-079X.1998.tb00538.x
62. Peplonska B, Bukowska A, Sobala W, Reszka E, Gromadzinska J, Wasowicz W, et al. Rotating night shift work and mammographic density. Cancer Epidemiol Biomarkers Prev. 2012;21:1028-37. http://dx.doi.org/10.1158/1055-9965.EPI-12-0005
63. Davis S, Kaune WT, Mirick DK, Chen C, Stevens RG. Residential magnetic fields, light-at-night, and nocturnal urinary 6-sulfatoxymelatonin concentration in women. Am J Epidemiol. 2001;154:591-600. http://dx.doi.org/10.1093/aje/154.7.591
64. Fernandez B, Malde JL, Montero A, Acu-a D. Relationship between adenohypophyseal and steroid hormones and variations in serum and urinary melatonin levels during the ovarian cycle, perimenopause and menopause in healthy women. J Steroid Biochem. 1990;35:257-262. http://dx.doi.org/10.1016/0022-4731(90)90282-W
65. Hsing AW, Meyer TE, Niwa S, Quraishi SM, Chu LW. Measuring serum melatonin in epidemiologic studies. Cancer Epidemiol Biomarkers Prev. 2010;19:932-937. http://dx.doi.org/10.1158/1055-9965.EPI-10-0004
66. Graham C, Cook MR, Kavet R, Sastre A, Smith DK. Prediction of nocturnal plasma melatonin from morning urinary measures. J Pineal Res. 1998;24:230-238. http://dx.doi.org/10.1111/j.1600-079X.1998.tb00538.x
67. Langley AR, Graham CH, Grundy AL, Tranmer JE, Richardson H, Aronson KJ. A cross-sectional study of breast cancer biomarkers among shift working nurses. BMJ Open. 2012. http://dx.doi.org/10.1136/bmjopen-2011-000532
68. Leonardi GC, Rapisarda V, Marconi A, Scalisi A, Catalano F, Proietti L, et al. Correlation of the risk of breast cancer and disruption of the circadian rhythm (Review). Oncol Rep. 2012;28: 418-428.
69. Kelleher FC, Rao A, Maguire A. Circadian molecular clocks and cancer. Cancer Lett. 2014;342:9-18. http://dx.doi.org/10.1016/j.canlet.2013.09.040
70. Zmrzljak UP, Rozman D. Circadian regulation of the hepatic endobiotic and xenobiotic detoxification pathways: the time matters. Chem Res Toxicol. 2012;25:811-824. http://dx.doi.org/10.1021/tx200538r
71. Gold DR, Rogacz S, Bock N, Tosteson TD, Baum TM, Speizer FE, et al. Rotating shift work, sleep, and accidents related to sleepiness in hospital nurses. Am J Public Health. 1992;82:1011-1014. http://dx.doi.org/10.2105/AJPH.82.7.1011
72. Bracci M, Copertaro A, Manzella N, Staffolani S, Strafella E, Nocchi L, et al. Influence of night-shift and napping at work on urinary melatonin, 17-β-estradiol and clock gene expression in pre-menopausal nurses. J Biol Regul Homeost Agents. 2013;27:267-274.
73. James FO, Cermakian N, Boivin DB. Circadian rhythms of melatonin, cortisol, and clock gene expression during simulated night shift work. Sleep. 2007;30:1427-1436.
74. Ando H, Ushijima K, Kumazaki M, Takamura T, Yokota N, Saito T, et al. Influence of age on clock gene expression in peripheral blood cells of healthy women. J Gerontol A Biol Sci Med Sci. 2010;65:9-13. http://dx.doi.org/10.1093/gerona/glp160
75. Reszka E, Peplonska B, Wieczorek E, Sobala W, Bukowska A, Gromadzinska J, et al. Circadian gene expression in peripheral blood leukocytes of rotating night shift nurses. Scand J Work Environ Health. 2013;39:187-94. http://dx.doi.org/10.5271/sjweh.3303
76. Akashi M, Soma H, Yamamoto T, Tsugitomi A, Yamashita S, Yamamoto T, Nishida E, Yasuda A, Liao JK, Node K. Noninvasive method for assessing the human circadian clock using hair follicle cells. Proc Natl Acad Sci U S A. 2010;107:15643-8. http://dx.doi.org/10.1073/pnas.1003878107
77. Ackermann K, Plomp R, Lao O, Middleton B, Revell VL, Skene DJ, Kayser M. Effect of sleep deprivation on rhythms of clock gene expression and melatonin in humans. Chronobiol Int. 2013;30:901-909. http://dx.doi.org/10.3109/07420528.2013.784773
78. Stevens RG. Circadian disruption and breast cancer: from melatonin to clock genes. Epidemiology. 2005;16:254-258. http://dx.doi.org/10.1097/01.ede.0000152525.21924.54
79. Balsalobre A, Brown SA, Marcacci L, Tronche F, Kellendonk C, Reichardt HM, Schütz G, Schibler U. Resetting of circadian time in peripheral tissues by glucocorticoid signaling. Science. 2000;289:2344-2347. http://dx.doi.org/10.1126/science.289.5488.2344
80. Manzella N, Bracci M, Staffolani S, Strafella E, Rapisarda V, Valentino M, Amati M, Copertaro A, Santarelli L. Styrene altered clock gene expression in serum-shocked cultured human fibroblasts. Biosci Biotechnol Biochem. 2013;77:1296-1298. http://dx.doi.org/10.1271/bbb.120944
81. Chunhui Y, Lina M, Irene A, Sochirca O, Arisio R, Yu H, et al. The circadian gene NPAS2 is a novel prognostic biomarker for breast cancer. Breast Cancer Res Treat. 2010;120: 663-669. http://dx.doi.org/10.1007/s10549-009-0484-0
82. Winter SL, Bosnoyan-Collins L, Pinnaduwage D, Andrulis IL. Expression of the circadian clock genes Per1 and Per2 in sporadic and familial breast tumors. Neoplasia. 2007;9: 797-800. http://dx.doi.org/10.1593/neo.07595
83. Zienolddiny S, Haugen A, Lie JA, Kjuus H, Anmarkrud KH, Kjærheim K. Analysis of polymorphisms in the circadian-related genes and breast cancer risk in Norwegian nurses working night shifts. Breast Cancer Res. 2013;15:R53. Epub ahead of print. http://dx.doi.org/10.1186/bcr3445
84. Dumont M, Lanctôt V, Cadieux-Viau R, Paquet J. Melatonin production and light exposure of rotating night workers. Chronobiol Int. 2012;29:203-210. http://dx.doi.org/10.3109/07420528.2011.647177
85. Skrinar GS, Bullen BA, Reppert SM, Peachey SE, Turnbull BA, McArthur JW. Melatonin response to exercise training in women. J Pineal Res. 1989;7:185-194. http://dx.doi.org/10.1111/j.1600-079X.1989.tb00666.x
86. Kennaway DJ, Lushington K, Dawson D, Lack L, van den Heuvel C, Rogers N. Urinary 6-sulfatoxymelatonin excretion and aging: new results and a critical review of the literature. J Pineal Res. 1999; 27:210-220. http://dx.doi.org/10.1111/j.1600-079X.1999.tb00617.x
87. Zeitzer JM, Daniels JE, Duffy JF, Klerman EB, Shanahan TL, Dijk DJ, et al. Do plasma melatonin concentrations decline with age? Am J Med. 1999;107:432-436. http://dx.doi.org/10.1016/S0002-9343(99)00266-1
88. Escames G, Ozturk G, Ba-o-Otálora B, Pozo MJ, Madrid JA, Reiter RJ, et al. Exercise and melatonin in humans: reciprocal benefits. J Pineal Res. 2012;52:1-11. http://dx.doi.org/10.1111/j.1600-079X.2011.00924.x
89. Stevens RG, Davis S, Mirick DK, Kheifets L, Kaune W. Alcohol consumption and urinary concentration of 6-sulfatoxymelatonin in healthy women. Epidemiology. 2000; 11:660-665. http://dx.doi.org/10.1097/00001648-200011000-00008
90. Grundy A, Sanchez M, Richardson H, Tranmer J, Borugian M, Graham CH, et al. Light intensity exposure, sleep duration, physical activity, and biomarkers of melatonin among rotating shift nurses. Chronobiol Int. 2009;26:1443-1461. http://dx.doi.org/10.3109/07420520903399987
91. Stevens RG. Electric power use and breast cancer: a hypothesis. Am J Epidemiol. 1987;125:556-561.
92. Rossetti S, Esposito J, Corlazzoli F, Gregorski A, Sacchi N. Entrainment of breast (cancer) epithelial cells detects distinct circadian oscillation patterns for clock and hormone receptor genes. Cell Cycle. 2012;11:350-360. http://dx.doi.org/10.4161/cc.11.2.18792
93. Nakamura TJ, Sellix MT, Kudo T, Nakao N, Yoshimura T, Ebihara S, Colwell CS, Block GD. Influence of the estrous cycle on clock gene expression in reproductive tissues: effects of fluctuating ovarian steroid hormone levels. Steroids. 2010;75:203-212. http://dx.doi.org/10.1016/j.steroids.2010.01.007
94. Nováková M, Sládek M, Sumová A. Human chronotype is determined in bodily cells under real-life conditions. Chronobiol Int. 2013;30:607-617. http://dx.doi.org/10.3109/07420528.2012.754455.