Did you know that the formulation of human breast milk changes pending time of day, throughout the course of the day and night? *cue brain explosion* I remember when I first read the research on this, and so many dots fell into place. For those who exclusively breast feed (i.e., not pump), this may seem irrelevant. However, as a working mum, who had both children start day-care at around the 6-month mark, whilst also wanting them to continue receiving the health benefits of breast milk, this was a revelation. Maybe this was the reason why my darling daughter was waking up, because she’d been fed breast milk that was pumped at 3pm?
Why does it matter? Whilst yes, you can feed your baby human breast milk that was pumped at 6am at 6pm, is it better to feed the baby milk that was pumped from a similar time of day? The answer is yes. And, whilst the following info is in no way intended for you to feel pressure to be able to pump human breast milk at specific times, science is science… so if it is practical for you to optimise the timing of pumping… why wouldn’t you?
Tell me more about the science
Human breast milk contains higher levels of cortisol and activity-promoting amino acids during the day, to promote alertness, feeding behaviour, and catabolic processes. During the night, human breast milk contains high levels of melatonin and tryptophan to foster sleep, relax digestion, and support cell restoration (Sanchez, 2013, Hahn-Holbrook, 2019).
Tryptophan is an amino acid which is linked with promoting sleep through the tryptophan/serotonin pathway. There is a well- established link between intake of tryptophan in human breast milk, and sleep patterns of breast-fed infants (Richard, 2009). When examining the overall cycle of tryptophan in human breast milk, lowest levels are found mid-afternoon, with peak at around 3am. As is expected, the level of melatonin itself is highest overnight, dropping during the day (Cubero, 2007).
So, what does this mean for the day to day?
Given what the science shows, if, like me, you rely on pumping through the day for milk for your baby for days to come, the following simple strategies can help ensure you are optimising your time as well.
- Pump at a similar time to what your baby will be fed. For example, if they usually take a milk feed at 11.30am, aim to pump at around 11.30am. If the exact time isn’t possible, aim to do it at as similar time to possible as you can.
- Purchase a ‘pumping bra’, so your hands are free whilst you pump – this means you can churn through the emails/wash the dishes/check out cute photos from day-care whilst you pump, leaving you with less down time through the day.
- Label your freezer bags of human breast milk. Not just with name, date and volume, but also with the time you pumped. If you’re super organised you may even store in the freezer in sections (e.g. morning, afternoon, night etc).
The fact that human breast milk changes composition pending time of day really is one of those ‘how cool is the human body’ moments, and with a few little tweaks, you ensure you are getting the timing right, to optimise the time-of-day human breast milk composition for your bub.
This post was sponsored by NiMera.
From time to time I write sponsored posts such as this, however views are entirely my own, and I only ever collaborate with companies and brands who resonate with me.
Cubero J. et al; Neuroendocrinology Letters (2007); 28(4): 360-366; Chrononutrition applied to formula milks to consolidate infants’ sleep/wake cycle
Hahn-Holbrook, J., Saxbe, D., Bixby, C. et al. (2019), Human milk as “chrononutrition”: implications for child health and development. Pediatr Res 85, 936–942. http://doi.org/10.1038/s41390-019-0368-x
Heine W. et al; Amino Acids (1995); 9(3): 91; The significance of tryptophan in human nutrition
Richard D.M. et al; International Journal of Tryptophan Research (2009); 2: 45-60; L-Tryptophan: Basic Metabolic Functions, Behavioral Research and Therapeutic Indications
Lerner, Aaron and Shamir, R, (2000). Nucleotides in infant nutrition: An update. IMAJ, Vol2, p772-773.
Sánchez, C. L. et al. (2013). Evolution of the circadian profile of human milk amino acids during breast feeding J. Appl. Biomed 11, 59-70