Melatonin, milk, and breast pumps: Does timing affect infant sleep?

© 2022 Gwen Dewar, Ph.D., all rights reserved

Does the composition of breast milk change over the course of the 24-hour mean solar day? Yes. The "drowsy" hormone, melatonin, reaches peak concentrations in breast milk at nighttime. C ortisol — a stress hormone that promotes alertness — is typically at its highest in the morning.

And so if you feed your baby milk that has been pumped and stored, it's probably a skilful idea to make sure the milk is "cyclic-matched." Researchers suspect that "mistimed" milk could contribute to sleep troubles, and possibly disrupt your baby'south developing circadian rhythms.

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Some researchers phone call it "chrononutrition," the idea that nosotros can ameliorate our slumber cycles and other daily rhythms by adjusting the timing of what we consume.

For example, some food ingredients make u.s. more than alert. Others brand us sleepy. And breast milk? Information technology might be able to do both, depending onwhen it'southward produced.

So perhaps it volition become standard operating procedure. Mothers who use breast pumps and store their chest milk will note thefourth dimension of twenty-four hours that their milk was expressed. When they feed their babies atnight, they'll use only milk that was producedafter dark.

And when parents use baby formulas? Maybe they'll utilise slightly different formulations depending on the time of mean solar day — to mimic the natural changes in chest milk.

Why exactly might this exist a good idea? In part, it has to do with the "drowsy" hormone, melatonin.

Consider, for case, a study of 5 breastfeeding mothers in Israel.

Researchers tracked changes in breast milk over time, testing milk every 2 hours for a 24-hour period. In particular, the researchers measured levels of melatonin, the hormone that makes us feel drowsy after nighttime.

Were there any differences between milk expressed during the solar day and milk expressed in the evening?

Yep, at that place were, and the researchers institute evidence of a articulate, circadian rhythm: Milk produced at nighttime contained higher concentrations of melatonin (Cohen Engler et al 2012).

Subsequent enquiry has confirmed these results.

For case, in a written report of 21 lactating mothers living in Frg, researchers didn't merely notice that melatonin levels were higher at night.They were v times higher than daytime levels (Katzer et al 2016).

Similarly, researchers in China accept documented dramatic changes across a 24-hr period.

Yishi Qin and her team tested the breast milk of 98 lactating mothers, and compared milk melatonin levels at 3pm, 9pm., and 3am (Qin et al 2019).

On average, melatonin levels at 9pm were virtually 3 times as high every bit melatonin levels at 3am. And the breast milk pumped in the center of the dark? At 3am?

That's when melatonin concentrations were at their pinnacle — nearly 10 times higher than melatonin levels in milk collected during the afternoon.

In that location'south also bear witness regarding the stress hormone cortisol: It reaches acme concentrations inmorn breast milk.

Cortisol helps make united states feel alert, and it's possible that babies could receive a heave in cortisol depending on the timing of breast milk production.

Forenoon levels are approximately iv times higher than levels present in breast milk produced in the evening (around 6pm). And they are near twice as high as levels present in milk expressed during the night (Pundir et al 2017; Italianer et al 2020).

Were in that location whatsoever differences between milk expressed during the twenty-four hour period and milk expressed in the evening? Aye, there were, and the researchers found bear witness of a clear, circadian rhythm. Milk produced at dark contained higher levels of melatonin (Cohen Engler et al 2012). It's not yet articulate if fluctuating levels of melatonin in breast milk influence infant slumber patterns. Time to come studies may provide answers.

Then there'due south the research regarding tryptophan.

Tryptophan is establish in breast milk, and it is used by the trunk to industry melatonin. Like melatonin, tryptophan levels ascent and fall according to a circadian rhythm, with concentrations peaking at night.

Practise babies who eat tryptophan in breast milk feel a rise in melatonin levels? There is some evidence to support the thought.

Javier Cubero and colleagues studied eight exclusively-breastfed infants, tracking changes in their mothers' chest milk and changes in the infants' melatonin levels. They besides monitored a control grouping of 8 formula-fed babies (Cubero et al 2005).

All the babies were approximately 12 weeks sometime, and they were each fed on the same schedule — once every iv hours. But there was a difference between groups. For breastfed babies, melatonin levels peaked a few hours after their mothers' tryptophan levels did. For formula-fed babies, the height in melatonin happened much later, and infants spent significantly less time sleeping at nighttime.

Did the tryptophan in chest milkcrusade differences in melatonin rhythms and sleep patterns?

That's non clear. Possibly, the link betwixt maternal tryptophan and infant sleep patterns was due to hazard. And even if information technology wasn't, we can't exist certain about causation.

Maybe something other than maternal tryptophan could explain why breastfed babies were unlike. For case, breastfed babies might have gotten more skin-to-peel contact, which lowered their stress levels and made it easier to sleep. Or peradventure the breastfeeding mothers in this study were more than likely to expose their babies to natural lighting patterns, which would have helped their babies adjust to the 24-hour twenty-four hour period.

And then I'yard interested in a study conducted by Sara Aparicio and colleagues (Aparicio et al 2007). These researchers tested the effects of dietary tryptophan past performing a double-blind experiment on formula-fed babies (Aparicio et al 2007).

There were three atmospheric condition:

• In the examination condition, babies got standard formula during the day and tryptophan-enriched formula at dark.
• In control condition #1, babies got standard formula, day and night.
• In control status #2, babies got tryptophan-enriched formula during the day (6am to 6pm) and regular formula at nighttime (6pm to 6am).

After a calendar week on the "night-time tryptophan" regimen, babies in the exam status showed improvements in their sleep patterns. Babies in the control groups did not.

So it seems that higher daytime tryptophan concentrations might assist young babies sleep better.

Other sleepy ingredients?

Melatonin and tryptophan aren't the only sleep-associated substances in breast milk. Cristina Sanchez and her colleagues note that several nucleotides—similar 5'UMP, 5'AMP, and 5'GMP—either induce sleepiness or help regulate circadian rhythms (Sanchez et al 2009).

These nucleotides are present in breast milk. Practise their concentrations in chest milk change over a 24-hour period? The researchers asked thirty women to express their chest milk at several different times of day. Then the milk was analyzed.

Nucleotide concentrations in chest milk did indeed change over a 24-hour period.

For example,5'UMP–which has a calming effect–peaked in the middle of the nighttime.

Andfive'AMP, which makes people feel drowsy, was at its highest concentration in breast milk that was expressed in the early night-time.

Can we assume that nucleotides in breast milk might aid infants fall asleep—and stay asleep—during the night?

To answer this, we demand some other experiment like that one conducted on formula-fed babies by Sara Aparicio's team. Some experiments have been conducted, only they involved food that was fortified withboth tryptophan and slumber-friendly nucleotides (Cubero 2006; Cubero et al 2007). As a result, nosotros don't know what result the nucleotides might have had on their own.

Does this mean that "mistimed" milk could affect an babe'southward beliefs?

More research is needed to answer this question, and the reality is bound to be complex. Simply equally Jennifer Hahn-Holbrook and her colleagues have noted, it'due south certainly plausible.

Animal studies confirm that the melatonin in chest milk "rapidly crosses the intestinal barrier and diffuses into many tissues, including the liver, kidney and brain" (Hahn-Holbrook et al 2019).

Information technology's also clear that glucocorticoids (similar cortisol) can pass from breast milk into a young rodent'south brain, and nosotros've good reason to call up that the aforementioned is true for humans (Hahn-Holbrook et al 2019).

And so information technology seems wise to presume that the timing of breast milk product could make a deviation. It may have an impact on an infant'southward behavior, and not merely in the minutes or hours afterwards a baby feeds.

Hahn-Holbrook and her colleagues signal out that a regular diet of "mistimed milk" might interfere the development of a baby's circadian rhythms, contributing to sleep problems. It might likewise alter an infant'south stress responses.

The good news? If mistimed milk really does present problems, these are easy to fix. We simply need to note the fourth dimension of day when milk is expressed, and avert giving our babies milk that is chronologically mismatched.

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More data near feeding, breast milk, and baby slumber

For more information about the opens in a new windowcomposition of breast milk, click here.

For more breastfeeding information, opens in a new window including tips most breast pumps, see these practical breastfeeding tips.

Struggling with a sleepless infant? Check out opens in a new windowthese evidence-based articles virtually the science of baby sleep.

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References: Chrononutrition, breast pumps, and baby formula

Aparicio S, Garau C, Esteban S, Nicolau MC, Rivero M, and Rial RV. 2007. Chrononutrition: utilise of dissociated day/night babe milk formulas to meliorate the development of the wake-sleep rhythms. Effects of tryptophan. Nutr Neurosci. 2007 Jun-Aug;ten(3-4):137-43.

Cohen Engler A, Hadash A, Shehadeh Northward, Pillar G. 2012. Breastfeeding may better nocturnal sleep and reduce infantile colic: potential part of breast milk melatonin. Eur J Pediatr. 171(4):729-32.

Cubero J, Valero Five, Sánchez J, Rivero G, Parvez H, Rodríguez AB, Barriga C. 2005. The circadian rhythm of tryptophan in breast milk affects the rhythms of 6-sulfatoxymelatonin and sleep in newborn. Neuro Endocrinol Lett. 26(6):657-61.

Cubero J, Narciso D, Terrón P, Rial R, Esteban S, Rivero M, Parvez H, Rodríguez AB, Barriga C. 2007. Chrononutrition applied to formula milks to consolidate infants' sleep/wake bicycle. Neuro Endocrinol Lett. 28(4):360-6.

Cubero J, Chanclón B, Sánchez Due south, Rivero Yard, Rodríguez AB, Barriga C. 2009. Improving the quality of infant sleep through the inclusion at supper of cereals enriched with tryptophan, adenosine-5′-phosphate, and uridine-5′-phosphate. Nutr Neurosci. 12(6):272-80.

Gila-Díaz A, Herranz Carrillo Chiliad, Cañas Southward, Saenz de Pipaón M, Martínez-Orgado JA, Rodríguez-Rodríguez P, López de Pablo ÁL, Martin-Cabrejas MA, Ramiro-Cortijo D, Arribas SM. 2020. Influence of Maternal Age and Gestational Age on Chest Milk Antioxidants During the Beginning Calendar month of Lactation. Nutrients. 12(ix):2569.

Glynn LM, Davis EP, Schetter CD, Chicz-Demet A, Hobel CJ, Sandman CA. 2007. Postnatal maternal cortisol levels predict temperament in healthy breastfed infants. Early Hum Dev. ;83(ten):675-81.

Gray KR, Davis EP, Sandman CA, Glynn LM. 2013. opens in a new windowHuman milk cortisol is associated with baby temperament. Psychoneuroendocrinology. 38(seven):1178-85.

Hahn-Holbrook J, Saxbe D, Bixby C, Steele C, Glynn Fifty. 2019. Homo milk as "chrononutrition": implications for child health and development. Pediatr Res. 85(7):936-942.

Harada T, Hirotani M, Maeda Grand, Nomura H, and Takeuchi H. 2007. Correlation betwixt breakfast tryptophan content and morning-evening in Japanese infants and students aged 0-15 yrs. J Physiol Anthropol. 26(2):201-7.

Hinde K, Skybiel AL, Foster AB, Del Rosso 50, Mendoza SP, and Capitanio JB. 2015. Cortisol in female parent's milk across lactation reflects maternal life history and predicts infant temperament. Behavioral Ecology 26 (ane): 269-281.

Katzer D, Pauli Fifty, Mueller A, Reutter H, Reinsberg J, Fimmers R, Bartmann P, Bagci South. 2016. Melatonin Concentrations and Antioxidative Capacity of Homo Breast Milk According to Gestational Historic period and the Fourth dimension of 24-hour interval. J Hum Lact. 32(iv):NP105-NP110.

Pundir S, Wall CR, Mitchell CJ, Thorstensen EB, Lai CT, Geddes DT, Cameron-Smith D. 2017. Variation of Homo Milk Glucocorticoids over 24 hour Period. J Mammary Gland Biol Neoplasia. 22(1):85-92.

Qin Y, Shi W, Zhuang J, Liu Y, Tang Fifty, Bu J, Sun J, Bei F. 2019. Variations in melatonin levels in preterm and term human breast milk during the first month after commitment. Sci Rep. 2022 9(1):17984.

Sánchez CL, Cubero J, Sánchez J, Chanclón B, Rivero M, Rodríguez AB, and Barriga C. 2009. The possible function of human milk nucleotides equally sleep inducers. Nutr Neurosci. 12(1):2-8.

van der Voorn B, de Waard M, van Goudoever JB, Rotteveel J, Heijboer Air-conditioning, Finken MJ. 2016. Breast-Milk Cortisol and Cortisone Concentrations Follow the Diurnal Rhythm of Maternal Hypothalamus-Pituitary-Adrenal Axis Activity. J Nutr. 146(11):2174-2179.

Content of "Breastfeeding and infant formula" last modified 3/2021

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