Melatonin is the hormone produced by the pineal gland that plays a role in regulating sleep and circadian rhythm. Exogenous administration of melatonin has no specific use during breastfeeding; however, endogenous melatonin is normally excreted into breastmilk and probably plays a role in regulating the infant's sleep cycle. One study attributed a slightly longer sleep time in breastfed infant than in formula-fed infants to melatonin in breastmilk. Some authors suggest that mothers should nurse in the dark at night in order to avoid reductions in the melatonin content of breastmilk, which could disturb infant sleep patterns. Differentiating milk pumped during the day from milk pumped during darkness has also been suggested for women pumping milk for their infants. No data exist on the safety of maternal use of melatonin during breastfeeding. However, doses higher than those expected in breastmilk after maternal supplementation have been used safely in infants. It is unlikely that short-term use of usual doses of melatonin in the evening by a nursing mother would adversely affect her breastfed infant.
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em>Maternal Levels.Melatonin is a normal component of human milk which is synthesized from the amino acid tryptophan.
Ten nursing mothers who were 3 to 5 days postpartum had serum and breastmilk melatonin levels measured between 2 pm and 5 pm and again between 2 am and 4 am. The breastmilk melatonin level averaged 23 ng/L at night, an average of 35% of the maternal serum concentration. Melatonin was undetectable (<10 ng/L) in milk during the daytime. Six of the mothers collected milk after each feeding for 24 hours once within 3 months of delivery. All mothers exhibited a marked circadian rhythm of melatonin excretion into breastmilk with detectable levels first occurring in the evening and dropping to undetectable levels in the morning.
Twenty-four healthy mothers and 24 mothers with allergic eczema were studied in a crossover fashion to watch either a humorous video, a nonhumorous video, or no video at 2-week intervals. Melatonin was measured in breastmilk 5 times between 10 pm and 6 am. Melatonin levels were higher at all times in the mothers who had watched the humorous video. The melatonin levels in mothers with eczema were generally lower than in normal mothers, but had a greater increase to similar levels in both groups after viewing the humorous video. The highest milk melatonin levels occurred at the 2 am sampling in all phases of the study, with a peak of 20.8 ng/L in healthy mothers and 19.9 ng/L in those with eczema.
In studies in which exogenous oral melatonin was given to women, the resulting serum melatonin was variable, but peak serum concentrations ranged from 1.1 to 2.6 mcg/L for each 1 mg administered. This would result in an average increase in breastmilk melatonin concentration from 0.4 to 1 mcg/L for each 1 mg administered to the mother, based on an average milk concentration of 35% of the maternal serum concentration. While the resulting concentrations would be higher than the typical physiologic peak milk concentrations of 0.02 mcg/L, it would present a considerably lower dose to the infant than the 10 mg/kg dosages of melatonin that have been safely administered to neonates in clinical studies.
One study found that breastmilk melatonin concentration was inversely correlated with breastmilk prolactin concentration and was higher in women experiencing fatigue in the morning.
Five nursing mothers provided breastmilk samples every 2 hours over a 24-hour period. Melatonin was undetectable during the day, but began to rise at about 8 pm, reaching a peak at about 3 am, and then declining.
A study of 8 breastfed and 6 formula-fed infants found different patterns of the melatonin metabolite, 6-sulfatoxymelatonin, in their urine. Breastfed infants had a sinusoidal excretion pattern with a peak at 6 am and a trough at 6 pm. Formula-fed infants had a simple increase in the metabolite that was at baseline between about 8 pm and 4 am with a peak at about noon.
Effects in Breastfed Infants:
Relevant published information was not found as of the revision date.
Possible Effects on Lactation:
Relevant published information was not found as of the revision date.
1. Arslanoglu S, Bertino E, Nicocia M, Moro GE. Potential chronobiotic role of human milk in sleep regulation. J Perinat Med. 2012;40:1-8. 2. Cohen Engler A, Hadash A, Shehadeh N, Pillar G. Breastfeeding may improve nocturnal sleep and reduce infantile colic: Potential role of breast milk melatonin. Eur J Pediatr. 2012;171:729-32. PMID:22205210 3. Sanchez-Barcelo EJ, Mediavilla MD, Reiter RJ. Clinical uses of melatonin in pediatrics. Int J Pediatr. 2011;2011:892624. PMID:21760817 4. Gitto E, Aversa S, Reiter RJ et al. Update on the use of melatonin in pediatrics. J Pineal Res. 2011;50:21-8. PMID:21029156 5. Illnerova H, Buresova M, Presl J. Melatonin rhythm in human milk. J Clin Endocrinol Metab. 1993;77:838-41. PMID:8370707 6. Kimata H. Laughter elevates the levels of breast-milk melatonin. J Psychosom Res. 2007;62:699-702. PMID:17540228 7. Fourtillan JB, Brisson AM, Gobin P et al. Bioavailability of melatonin in humans after day-time administration of D(7) melatonin. Biopharm Drug Dispos. 2000;21:15-22. PMID:11038434 8. DeMuro RL, Nafziger AN, Blask DE et al. The absolute bioavailability of oral melatonin. J Clin Pharmacol. 2000;40:781-4. PMID:10883420 9. Markantonis SL, Tsakalozou E, Paraskeva A et al. Melatonin pharmacokinetics in premenopausal and postmenopausal healthy female volunteers. J Clin Pharmacol. 2008;48:240-5. PMID:18071190 10. Groer M, Davis M, Casey K et al. Neuroendocrine and immune relationships in postpartum fatigue. MCN Am J Matern Child Nurs. 2005;30:133-8. PMID:15775810 11. Cubero J, Valero V, Sanchez J et al. The circadian rhythm of tryptophan in breast milk affects the rhythms of 6-sulfatoxymelatonin and sleep in newborn. Neuro Endocrinol Lett. 2005;26:657-61. PMID:16380706
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