There are new studies on Breast Milk that show that the Breast milk expressed at different times of the day have different amounts of hormones present for example melatonin the sleep hormone is higher in the breast milk expressed in the evening. Here is a section of the article below.
Trytophan and circadian rhythms
One possibility is the amino acid tryptophan. Tryptophan is used by the body to manufacture melatonin, the hormone that makes us feel drowsy.
Tryptophan is found in breast milk, but the amount depends on the time of day. Tryptophan levels rise and fall according to a circadian rhythm, with concentrations peaking at night.
So it seems plausible that babies who consume tryptophan in breast milk would show similar circadian rhythms in their melatonin production. Each night, babies consume tryptophan in breast milk. Then their bodies use this tryptophan to make melatonin.
There is some supporting evidence for this. Javier Cubero and colleagues studied 8 exclusively-breastfed infants, tracking changes in their mothers’ breast milk and changes in the infants’ melatonin levels.
The researchers also examined a control group of 8 formula-fed infants (Cubero et al 2005).
In both groups, babies were 12 weeks old. They were fed every 4 hours.
The results? For breastfed babies, melatonin levels peaked a few hours after their mothers’ tryptophan levels did.
By contrast, formula-fed babies–who didn’t get any “mother-made” tryptophan–peaked much later. And compared with the breastfed babies, formula-fed infants spent significantly less time sleeping at night.
Written by Cristina Sanchez
To read the whole article follow link http://www.parentingscience.com/breast-pumps-and-baby-formula.html