Document Detail

The circadian rhythm of tryptophan in breast milk affects the rhythms of 6-sulfatoxymelatonin and sleep in newborn.
MedLine Citation:
PMID:  16380706     Owner:  NLM     Status:  MEDLINE    
INTRODUCTION: The hormone melatonin regulates the sleep and this pineal hormone is synthesized in the organism from the amino acid tryptophan. It is known that breast-fed babies have better sleep patterns and a better entrained sleep/wake cycle than bottle-fed babies (adapted formula). OBJECTIVE: To compare the circadian rhythm of 6-sulfatoxymelatonin (aMT6s)--the metabolite of melatonin excreted in the urine--in urine of bottle-fed and breast-fed children, and relate it to the circadian rhythm of tryptophan in breast milk, also evaluating the possible effects on the baby's night-time rest. METHODS: 16 infants of 12 weeks of age were studied, divided into two groups depending on their exclusively natural or artificial feeding. The circadian rhythm of 6-sulfatoxymelatonin in urine was measured for the two groups of infants and for the breast-feeding mothers. In the breast milk, the circadian rhythm of the amino acid tryptophan was measured. The rest of the infants was tested by wrist actimeters for a week and the sleep parameters of the infants were measured and evaluated. RESULTS: The tryptophan in the breast milk presented a circadian rhythm with acrophase at around 03:00. This affected the 6-sulfatoxymelatonin circadian rhythm with acrophase at 06:00 in the breast-fed infants, and also promoted nocturnal sleep. Assumed sleep, actual sleep, and sleep efficiency were significantly increased in the breast fed infants with respect the formula fed infants. CONCLUSION: A temporal relationship was observed between the circadian rhythm of 6-sulfatoxymelatonin of the exclusively breast-fed babies and that of tryptophan in the mother's milk. Acting this amino acid as a zeitgeber entrainment of the biological rhythms in the breast-fed infant.
J Cubero; V Valero; J Sánchez; M Rivero; H Parvez; A B Rodríguez; C Barriga
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Publication Detail:
Type:  Clinical Trial; Comparative Study; Journal Article; Research Support, Non-U.S. Gov't    
Journal Detail:
Title:  Neuro endocrinology letters     Volume:  26     ISSN:  0172-780X     ISO Abbreviation:  Neuro Endocrinol. Lett.     Publication Date:  2005 Dec 
Date Detail:
Created Date:  2006-03-16     Completed Date:  2006-06-02     Revised Date:  2006-11-15    
Medline Journal Info:
Nlm Unique ID:  8008373     Medline TA:  Neuro Endocrinol Lett     Country:  Sweden    
Other Details:
Languages:  eng     Pagination:  657-61     Citation Subset:  IM    
Department of Physiology, Faculty of Science, Extremadura University, Avda de Elvas s/n, 06071 Badajoz, Spain.
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MeSH Terms
Bottle Feeding
Breast Feeding
Circadian Rhythm / physiology*
Infant, Newborn
Melatonin / analogs & derivatives*,  urine
Milk, Human / metabolism*
Reference Values
Sleep / physiology*
Statistics, Nonparametric
Tryptophan / metabolism*
Reg. No./Substance:
2208-40-4/6-sulfatoxymelatonin; 73-22-3/Tryptophan; 73-31-4/Melatonin

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

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