Researchers found that breast milk hormones vary by time of day, and feeding expressed milk at the wrong time could affect infant sleep.
A new study suggests the timing of expressed breast milk could influence babies’ sleep patterns, as its hormonal makeup shifts throughout the day.
Researchers writing in Frontiers in Nutrition reported that breast milk contains hormones such as melatonin and cortisol that regulate circadian rhythms. Melatonin peaks around midnight, while cortisol is highest in the early morning. Feeding milk expressed at a different time of day may disrupt infants’ developing sleep cycles.
“Breast milk is a dynamic food: Consideration should be given to the time it is fed to the infant when expressed breast milk is used,” said lead researcher Melissa Woortman of Rutgers University. Senior investigator Maria Gloria Dominguez-Bello added that labeling milk as morning, afternoon or evening could help “preserve the natural hormonal and microbial composition of the milk, as well as circadian signals.”
Doctors continue to regard breast milk as the most complete form of infant nutrition.