Document Detail

Light and exercise and melatonin production in women.
MedLine Citation:
PMID:  16207802     Owner:  NLM     Status:  MEDLINE    
Melatonin may protect against breast cancer. Light and other factors influence melatonin, but the evidence is limited. The authors conducted a study to determine factors related to melatonin. Women volunteers recruited in Toronto, Canada, from 2002 to 2004 collected urine for three nights (winter and summer), took periodic light measurements, and recorded exposures in a diary. The relation of each variable to log-transformed creatinine-corrected 6-sulfatoxymelatonin in overnight urine was determined by use of generalized estimating equation linear regression. The final model was based on 1,054 measurement days from 213 participating women. None of the light variables was related to the log of 6-sulfatoxymelatonin. A significant interaction between season and day length was included in the final model. The most significant factor was duration of exercise (beta = 0.072; p = 0.004, two-tailed), which increased the amount of melatonin produced. Exercise duration later in the day was more significant (beta = 0.108; p = 0.0009, two-tailed). There was no difference between moderate or strenuous exercise. The failure to find a relation between light brightness and melatonin may be due to the difficulty of measuring this, as well as the importance of the light spectrum, which could not be measured. It is possible that the protective effect of exercise with respect to breast cancer may operate in part through an effect on melatonin.
Julia A Knight; Suzanne Thompson; Janet M Raboud; Barry R Hoffman
Publication Detail:
Type:  Journal Article; Research Support, Non-U.S. Gov't     Date:  2005-10-05
Journal Detail:
Title:  American journal of epidemiology     Volume:  162     ISSN:  0002-9262     ISO Abbreviation:  Am. J. Epidemiol.     Publication Date:  2005 Dec 
Date Detail:
Created Date:  2005-11-24     Completed Date:  2006-01-05     Revised Date:  2006-11-15    
Medline Journal Info:
Nlm Unique ID:  7910653     Medline TA:  Am J Epidemiol     Country:  United States    
Other Details:
Languages:  eng     Pagination:  1114-22     Citation Subset:  IM    
Prosserman Centre for Health Research, Samuel Lunenfeld Research Institute, Mount Sinai Hospital, Toronto, Ontario, Canada.
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MeSH Terms
Age Distribution
Alcohol Drinking / epidemiology
Anti-Inflammatory Agents, Non-Steroidal / therapeutic use
Body Size / physiology
Contraceptives, Oral, Hormonal / therapeutic use
Cross-Sectional Studies
Exercise / physiology*
Life Style
Melatonin / analogs & derivatives,  biosynthesis*,  urine
Multivariate Analysis
Ontario / epidemiology
Reference Values
Women's Health*
Reg. No./Substance:
0/Anti-Inflammatory Agents, Non-Steroidal; 0/Contraceptives, Oral, Hormonal; 2208-40-4/6-sulfatoxymelatonin; 73-31-4/Melatonin

From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine

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