Viral TikTok shares pumping hack for ‘day milk’ and ‘night milk’ to help babies sleep better

Pumping, mama? The time of day you pump—and then when you offer that pumped milk—might help your baby sleep better. In the latest installment of breast milk is magic: Breast milk produced in the morning is different from breast milk produced at night—and that might change how you label your pumped milk going forward.

In a now-viral TikTok, @aubreymarie explains why. “So I just found out that nighttime breast milk has melatonin in it, and daytime breast milk has cortisol in it, which helps with energy, alertness and focus,” she says. 

@theaubreymarie Breastmilk is so wild! #pumpingmom #pumpingmama #breastfeedingjourney #firsttimemom #breastmilkstillbestforbabies😊 #breastmilkhack #pumpinghack ♬ original sound – Aubrey Marie

Research backs this up: Breast milk pumped in the morning has more cortisol in it than milk that’s pumped at night, whereas milk made at night contains higher levels of both melatonin and tryptophan, which are helpful in inducing sleep. 

Related: Exclusively pumping is still breastfeeding, mama

The findings are an example of chrononutrition at work: the interaction of how what we eat and when we eat it can influence health. It follows then that offering morning-pumped milk to your little one in the a.m. might help them be more alert and engaged, while offering nighttime-pumped milk to your baby in the evenings might help them sleep better. 

“So I started separating my pumped milk in AM and PM…” she explains, “I just found all this out but now I make sure to label which is AM and which is PM and [my baby] has been sleeping really good, so I wonder if this is helping.” 

What does cortisol do?

Cortisol is a hormone with a lot of responsibilities: It helps with metabolism, regulates blood sugar and supports memory. (It also surges when we are stressed.)

For all these reasons, cortisol is a good hormone to have onboard during the day. It makes sense that mothers have more of it during waking hours, and therefore pass more of it on to their babies via their breast milk. Infants don’t start producing their own cortisol until around 6 weeks of age.

But note that higher levels of cortisol in breast milk don’t seem to relate to how much or how often babies cry. In other words, don’t worry: Your stressful day at work does not mean that your baby is destined for a night of crying.

Cortisol production is highest at 6 a.m., and slowly decreases throughout the daylight hours. 

Related: Mom calculates average of 2,388 hours spent exclusively pumping in viral TikTok

What does melatonin do?

Melatonin is a hormone that encourages sleep and relaxation. And because infants can’t yet produce melatonin themselves, breast milk is their sole source. 

Melatonin production peaks in adults between 2 a.m. and 4 a.m., so if you’re aiming to stock up on bedtime-ready milk, maybe consider adding a pumping session somewhere in that window.

One study also found that the levels of melatonin in breast milk that was pumped and then frozen didn’t change in its levels of melatonin, so know that storing your milk has no effect on the hormone composition.  

How to label pumped breast milk—use the date and time

If you are providing pumped milk to your baby, this information may impact how you do just that. 

Pumping hack: Consider labeling not only the date you pumped each bag of milk but also the time of day: AM or PM. That 9 a.m. bag of breast milk might not be the best choice for a before-bedtime feeding, as the higher levels of cortisol may make it harder for them to fall asleep. If you can, choose milk that was pumped later in the day or at night so the higher levels of melatonin can lull your baby into sweet slumber.

Related: Sleep like a baby: Your expert guide to 12 months of rest

Like so much in motherhood, take this advice as it works best for you and your family. If you are able to save melatonin-rich breast milk for nighttime feedings, great! This may be particularly helpful information if you’ve been experiencing sleep struggles—it certainly can’t hurt to try this approach and see if it helps.

But try not to let it stress you out. Remember that every single time your baby gets breast milk they benefit from it, regardless of what time of day it was pumped. So if these recommendations won’t work for you, don’t worry: Your baby will be just fine.

This story was originally published on August 22, 2019. It has been updated.

Sources

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(4):729-732. doi:10.1007/s00431-011-1659-3

​​Cubero J, Valero V, Sánchez 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(6):657-661.

Illnerová H. Buresová M. Presl J. Melatonin rhythm in human milk. The Journal of Clinical Endocrinology & Metabolism, Volume 77, Issue 3, 1 September 1993, Pages 838–841, https://doi.org/10.1210/jcem.77.3.8370707

Molad M, Ashkenazi L, Gover A, et al. Melatonin stability in human milk. Breastfeed Med. 2019;14(9):680-682. doi:10.1089/bfm.2019.0088 

Pundir, S., Wall, C.R., Mitchell, C.J. et al. Variation of Human Milk Glucocorticoids over 24 hour Period. J Mammary Gland Biol Neoplasia 22, 85–92 (2017). doi:10.1007/s10911-017-9375-x