Storing breast milk for specific times of day could support babies' circadian rhythm

image via Medical Xpress - medical research advances and health news

September 5, 2025, 4:00 AM

• •Breast milk contains bioactive components that vary based on the time of day.
• •Melatonin levels peak at midnight, while cortisol is highest in the early morning.
• •The study examined 236 breast milk samples from 21 participants.
• •Feeding expressed milk according to the time of expression could enhance benefits.

Researchers found that the composition of breast milk varies throughout the day, with hormones like melatonin and cortisol fluctuating significantly. These fluctuations could influence infant circadian rhythms, suggesting the timing of expressed milk feeding may be critical. The study examined breast milk samples for various components, including hormones and immune factors, and found differences based on the time of day and the age of the infant. The findings suggest that labeling and feeding expressed milk according to the time it was expressed could maximize the benefits of breast milk, aligning with natural biological rhythms.

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