This Article Full Text Full Text (PDF) Alert me when this article is cited Alert me if a correction is posted Services Similar articles in this journal Similar articles in PubMed Alert me to new issues of the journal Download to citation manager Citing Articles Citing Articles via HighWire Citing Articles via Google Scholar Google Scholar Articles by Schernhammer, E. S. Articles by Hankinson, S. E. Search for Related Content PubMed PubMed Citation Articles by Schernhammer, E. S. Articles by Hankinson, S. E.

Epidemiology of Urinary Melatonin in Women and Its Relation to Other Hormones and Night Work

¹ Channing Laboratory, Department of Medicine, Brigham and Women's Hospital and Harvard Medical School, Boston, Massachusetts; Departments of ² Epidemiology, ³ Biostatistics, ⁴ Nutrition, and ⁵ Environmental Health, Harvard School of Public Health, Boston, Massachusetts; ⁶ Ludwig Boltzmann-Institute for Applied Cancer Research, KFJ-Spital, Vienna, Austria; ⁷ Epidemiology Program, Dana Farber/Harvard Cancer Center, Boston, Massachusetts; and ⁸ Harvard Center for Cancer Prevention, Boston, Massachusetts

Requests for reprints: Eva S. Schernhammer, Channing Laboratory, 181 Longwood Avenue, Boston, MA 02115. Phone: (617) 525-4648; Fax: (617) 525-2008. E-mail: eva.schernhammer{at}channing.harvard.edu

Objective: Light exposure during night work suppresses melatonin production, and night work has been associated with an increased cancer risk. There is little information, however, about the interrelationships of night work, urinary melatonin levels, and levels of plasma steroid hormones in women. Method: We examined the reproducibility of morning urinary measurements of 6-sulfatoxymelatonin over a 3-year period in 80 premenopausal women. We assessed correlations between average urinary melatonin and plasma steroid hormone levels and evaluated potential associations between night work and hormone levels, using current and long-term shift work information from two large, prospective cohorts, the Nurses' Health Study cohorts. Results: The intraclass correlation for creatinine-adjusted 6-sulfatoxymelatonin was 0.72 (95% confidence interval, 0.65, 0.82). We found significantly increased levels of estradiol after longer durations of night work (geometric mean levels of estradiol, 8.8 pg/mL for women who never worked night shifts versus 10.1 pg/mL for women who worked 15 or more years of night shifts; P for trend = 0.03). We observed a significant inverse association between increasing number of nights worked within the 2 weeks preceding urine collection and urinary melatonin levels (r = –0.30, P = 0.008), but no association of recent night work with estradiol (r = 0.10, P = 0.41). Conclusion: A single morning urinary melatonin measurement is a reasonable marker for long-term melatonin levels among premenopausal women. Women who work on rotating night shifts seem to experience changes in hormone levels that may be associated with the increased cancer risk observed among night-shift workers.

Key Words: melatonin • estrogens • night work

This article has been cited by other articles:

				D. L. Brown, D. Feskanich, B. N. Sanchez, K. M. Rexrode, E. S. Schernhammer, and L. D. Lisabeth Rotating Night Shift Work and the Risk of Ischemic Stroke Am. J. Epidemiol., June 1, 2009; 169(11): 1370 - 1377. [Abstract] [Full Text] [PDF]

				E. S. Schernhammer and S. E. Hankinson Urinary Melatonin Levels and Postmenopausal Breast Cancer Risk in the Nurses' Health Study Cohort Cancer Epidemiol. Biomarkers Prev., January 1, 2009; 18(1): 74 - 79. [Abstract] [Full Text] [PDF]

				D. K. Mirick and S. Davis Melatonin as a Biomarker of Circadian Dysregulation Cancer Epidemiol. Biomarkers Prev., December 1, 2008; 17(12): 3306 - 3313. [Abstract] [Full Text] [PDF]

				C. Nagata, Y. Nagao, S. Yamamoto, C. Shibuya, Y. Kashiki, and H. Shimizu Light Exposure at Night, Urinary 6-Sulfatoxymelatonin, and Serum Estrogens and Androgens in Postmenopausal Japanese Women Cancer Epidemiol. Biomarkers Prev., June 1, 2008; 17(6): 1418 - 1423. [Abstract] [Full Text] [PDF]

				A. H. Wu, R. Wang, W.-P. Koh, F. Z. Stanczyk, H.-P. Lee, and M. C. Yu Sleep duration, melatonin and breast cancer among Chinese women in Singapore Carcinogenesis, June 1, 2008; 29(6): 1244 - 1248. [Abstract] [Full Text] [PDF]

				C. Nagata, T. Matsubara, T. Hara, H. Fujita, Y. Nagao, S. Yamamoto, C. Shibuya, Y. Kashiki, and H. Shimizu Urinary 6-Sulfatoxymelatonin and Mammographic Density in Japanese Women Cancer Epidemiol. Biomarkers Prev., November 1, 2007; 16(11): 2509 - 2512. [Abstract] [Full Text] [PDF]

				A. N. Viswanathan, S. E. Hankinson, and E. S. Schernhammer Night Shift Work and the Risk of Endometrial Cancer Cancer Res., November 1, 2007; 67(21): 10618 - 10622. [Abstract] [Full Text] [PDF]

				I. Figa-Talamanca Occupational risk factors and reproductive health of women Occup. Med., December 1, 2006; 56(8): 521 - 531. [Abstract] [Full Text] [PDF]

				T. Kubo, K. Ozasa, K. Mikami, K. Wakai, Y. Fujino, Y. Watanabe, T. Miki, M. Nakao, K. Hayashi, K. Suzuki, et al. Prospective Cohort Study of the Risk of Prostate Cancer among Rotating-Shift Workers: Findings from the Japan Collaborative Cohort Study Am. J. Epidemiol., September 15, 2006; 164(6): 549 - 555. [Abstract] [Full Text] [PDF]

				E. S. O'Leary, E. R. Schoenfeld, R. G. Stevens, G. C. Kabat, K. Henderson, R. Grimson, M. D. Gammon, M. C. Leske, and for the Electromagnetic Fields and Breast Cancer o Shift Work, Light at Night, and Breast Cancer on Long Island, New York Am. J. Epidemiol., August 15, 2006; 164(4): 358 - 366. [Abstract] [Full Text] [PDF]

				H. Chen, E. Schernhammer, M. A. Schwarzschild, and A. Ascherio A Prospective Study of Night Shift Work, Sleep Duration, and Risk of Parkinson's Disease Am. J. Epidemiol., April 15, 2006; 163(8): 726 - 730. [Abstract] [Full Text] [PDF]

				P. K. Verkasalo, K. Lillberg, R. G. Stevens, C. Hublin, M. Partinen, M. Koskenvuo, and J. Kaprio Sleep Duration and Breast Cancer: A Prospective Cohort Study Cancer Res., October 15, 2005; 65(20): 9595 - 9600. [Abstract] [Full Text] [PDF]

				E. S. Schernhammer and S. E. Hankinson Urinary Melatonin Levels and Breast Cancer Risk J Natl Cancer Inst, July 20, 2005; 97(14): 1084 - 1087. [Abstract] [Full Text] [PDF]

				R. G. Stevens and E. Schernhammer Epidemiology of Uriniary Melatonin in Women and Its Relation to Other Hormones and Night Work Cancer Epidemiol. Biomarkers Prev., February 1, 2005; 14(2): 551 - 551. [Full Text] [PDF]

				D. J. Kennaway The role of circadian rhythmicity in reproduction Hum. Reprod. Update, January 1, 2005; 11(1): 91 - 101. [Abstract] [Full Text] [PDF]