Melatonin

Lactation Celebration Week part 4. Melatonin…a real snooze fest.

What is it?

Melatonin is a sleep inducing hormone produced in the brain, specifically, the pineal gland. Tryptophan is broken down by your body to make melatonin (and serotonin). After a meal, melatonin can be released at 400 times the amount the pineal produces at night…400 times! Ever wonder why you get sleepy after you eat a meal? Melatonin, that’s why.

Side note: did you know that adequate Vitamin D levels increases the enzyme that breaks down tryptophan which allows higher levels of serotonin and melatonin to be made?

Why is it in human milk?

• Regulates circadian rhythm:

  • Humans don’t start producing their own melatonin until about 3-4 months of age.

    • The higher the level of melatonin in one’s body, the more tired they get.

    • It is produced and released by the brain in response to lowering light levels. The highest levels of melatonin are around 3-4 in the morning. Production stops abruptly when light levels increase, but since melatonin has a 1/2 life of about 30 min, you don’t typically wake immediately when the sun shines in your bedroom.

    • Melatonin levels are altered by artificial blue light (phones, TV, room lights) as well as the sun, which is why it is recommended to stop using electronic devices a few hours before you want to go to sleep.

  • The melatonin in human milk helps regulate the baby’s day/night cycle (circadian rhythm)….although if you are a new parent, most nights it probably doesn’t seem like it!

  • Melatonin is released into breastmilk in higher quantities at night.

  • Melatonin values vary by study. The difference in numbers may have to do with how the studies were designed and the postpartum day on which they measured melatonin.

    • In 2016, researchers measured melatonin levels in milk from parents who were 5-10 days postpartum. They found approx 7.3 pg/ml at night vs 1.5 pg/ml during the day.

    • In 2019, researchers measured milk from parents at 4 different time points (0-7days, 8-14 days, and 15-30 days postpartum) 2.4 pg/ml at 3pm vs 23.49 pg/ml at 3am.

      • They also found milk for preterm babies always had higher values (at all 4 time points) than full term milk.

      • Colostrum (0-7 days) contains more melatonin than transitional (7-14 days) or mature (15-30days) milk.

        • There isn’t really an exact time when milk is colostrum vs transitional vs mature. It’s a process that varies from human to human but for research purposes, it must be defined.

• Antioxidant

  • Oxidative stress, an imbalance of free radicals and antioxidant agents, can cause a host of health issues such as diabetes, cardiovascular disease, arthritis, asthma, high blood pressure, cancer, neurodegenerative disorders, psychiatric disorders, and more.

    • Babies who are formula fed are at higher risk of developing these chronic illnesses

  • It is normal for the body to produce free radicals and antioxidants, however not all of these mechanisms are developed at birth…human milk is perfectly designed to make up for these deficits.

  • Preterm infants are at high risk of developing necrotizing enterocolitis (NEC) in which oxidative stress is thought to play an important role.

• Immunity

  • In colostrum, melatonin has been shown to increase colostrum’s ability to fight bacteria in people with normal blood sugar levels but not people with high blood sugar levels.

  • Some studies show that using melatonin, usually in conjunction with vitamin D and zinc, may be helpful in preventing and treating RNA viruses such as covid19 and influenza.

Is it available in infant formula?

Nope.

Does it matter what time I give my baby my expressed milk?

For preterm (NICU) babies, due to melatonin’s antioxidant effects, it may be beneficial to give pumped milk at the same or similar time of day as when it was pumped but more research is needed on the benefits to this.

For life outside the NICU (let me jump on my soapbox), instructing parents to give pumped milk only at the time of the day that it was pumped is another barrier to providing human milk for human babies.

Most parents don’t have the supply or luxury of time to do this. Pumping parents pump when they need to pump, often based on when they have breaks at work. And many parents pump at night before they go to bed.

New parents don’t need more rules restricting when to give their baby human milk. Replacing human milk with formula because it is “mis-timed” comes with it’s own health implications.

In real life, it makes the most sense to give the milk you have to your baby when your baby is hungry, not based on the time of day.