Your breast milk offers not only immune-boosting components and nutrition, but also circadian signals, which can help build the baby's circadian rhythms during its growing period. The components in the breast milk vary not only in different time periods after the baby’s born, but on different time of a day.
Circadian signals in breast milk
Researchers recently found that there may be some circadian signals in the breast milk which can tell the infants the difference between day- and night-time, thus help program infant circadian rhythms.
How breast milk shows the circadian signals
The components in breast milk changes dramatically over the course of the day.
For example, levels of cortisol, a hormone that promotes alertness, are three times higher in morning milk than in evening milk. By contrast, melatonin, a hormone that promotes sleep and digestion, reaches the peak at midnight, but can hardly be found in the daytime milk.
There are higher levels of certain DNA building blocks that help promote healthy sleep in night milk, whereas more activity-promoting amino acids are found in day milk.
Scientists also found different peaks of levels of minerals. For example, iron peaks at around noon; magnesium, zinc, potassium and sodium peak in the morning. Vitamin E, which is good for the infant’s brain health, peaks in the evening.
|Compoment||Function||Levels in morning milk||Levels in evening milk|
|Melatonin||Promotes sleep and digestion||Low to zero||High, peaks in|
|DNA building blocks||Promotes healthy sleep||Low||High|
|Amino acids||Promotes activeness||High||Low|
Label your pumped milk with time
Over 85% of breastfeeding mothers in the U.S. have pumped their milk and refrigerated it for use, according to a 2005 – 2007 survey.
Scientists are not sure yet what effects would appear on babies who drink night milk in the morning, or morning milk in the late afternoon. But the differences in levels of hormones must have some meanings.
Admittedly, morning milk with high cortisol and night milk with high melatonin may provide just the same things to your baby nutritionally.
However, if circadian signals do help to calibrate the baby's circadian biology (which it seems so), then drinking "mistimed" milk may lead to difficulties in sleeping, digestion and overall development of the baby.
What to do
The best way to do is to label the pumped milk with time and offer babies the time-right milk. Considering the fact that the majority of American mothers are applying pumps and refrigeration, give the baby just what it needs at a certain time will be wise and proper.
If labeling time on the pumped breast milk can be standardized, thousands of infants may benefit from milk served at the right time. Circadian rhythms of the babies may also be better built, thus parents can enjoy a peaceful night without baby monitors beeping at midnight.
Magical links between mothers and infants
Breast milk changes as your little one grows, and there are also some magical links regarding immune systems between you and your baby.
At the beginning of breast feeding, the milk, called colostrum, is thick, honey-textured liquid with immunological components that perform as the first vaccination to protect your newborn.
The major immune booster is called secretory immunoglobulin A (SIgA), which coats the internal organs and lining of the digestive, respiratory and reproductive tracts. By preventing bacteria and pathogens to get in through the gut, SIgA protects your baby from the inside out.
After the first vaccination for about 2 or 3 days, the breast milk changes in texture and increases in volume. This is known as transitional milk which lasts about 3 to 7 days, ending in transforming into mature milk.
After 2 weeks of breast feeding, the breast milk turns into mature milk. Mature milk doesn’t vary a lot from colostrum: they contain basically the same properties, but mature milk is more diluted and is larger in volume.
Magical communication you won't think about
Components in mature milk is not unchangeable. The substances in mature milk can be influenced by:
The mother’s diet
Bacteria and viruses in the environment
The baby’s feeding behaviors
A magical thing is that it seems baby can pass on a cue through her saliva to the mother, telling her it’s sick and needs help, and the mother’s body will produce more milk with illness-specific antibodies.
Similarly, if a mother is ill, she will produce antibodies and pass them to the baby through breast milk for protection.
Researchers don’t know how exactly this works yet, but these things do happen.