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Breastfeeding May Improve Nocturnal Sleep and Reduce Infantile Colic: Potential Role of Breast Milk Melatonin

Exclusively breastfed infants had less colic and fussiness, and slept longer. Melatonin, which promotes sleep, available only in breastmilk, showed a clear relationship to infant sleep patterns.

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  • N: 94
  • Subject Ages: Infants ages 2 to 4 months
  • Location: Not available
  • SES: Not available
  • Eligibility: Not available
  • Additional:
    • Breastfeeding infants: Mean weight 5.36 kg; mean gestational age at birth of 39.2 weeks
    • Formula-fed infants: Mean weight 5.79 kg; mean gestational age at birth of 39.0 weeks


  1. Maternal melatonin passes through milk to the infant, and as a result, the infant will have a better nocturnal sleep, earlier establishment of circadian rhythm and decreased incidents of infantile colic.
  2. Melatonin has a relaxing effect on the gastrointestinal system and has a hypnotic effect.

Variables Measured, Instruments Used

  • Irritability/potential infantile colic and sleep characteristics - questionnaire
  • Melatonin levels in breastmilk and formula - ELISA




  1. Exclusively breastfed infants had lower incidence of colic attacks, less severe levels of irritability and longer durations of sleep.
  2. The breastfed infants had more fragmented sleep, but the overall duration of wakefulness at night was similar in both groups.
  3. No melatonin was measured in formula. Melatonin showed a clear circadian curve in human milk.
  4. There was a significant difference in the weight of formula-fed versus breastfed babies, with breastfed babies being significantly lighter.


  • Sample is convenience, not random, so possible selection bias.
  • Potential psychosocial bias, such as socioeconomic status, the family-unit composition, etc.
  • Data based on self-report