Circadian Rhythms and Breastfeeding

I recently wrote an article for the Linn Benton Lincoln Breastfeeding Coalition here and I am republishing it here.

Most mothers and families are familiar with the tiredness that comes with parenting a newborn. Often the baby will sleep for long periods during the day, only to wake up frequently at night. This apparent day-night reversal is exhausting and can be frustrating for both parents who (unless they do shift work) are used to being alert and active during the day and sleeping deeply and for long periods at night.

I recently attended a session in the Gold Lactation Online Conference entitled, “Breast Milk and Sleep: Circadian Rhythms in Human Milk.” It was a fascinating session because in it, Briana Tilman, IBCLC, LLL Leader and first year medical school student, describes how our circadian rhythms work, what drives them, and what can disrupt them. She explains how babies are born without most of the hormonal systems necessary for circadian rhythms functioning, and how it takes time for them to develop. She then gives information and calls for further research, and gives ideas families can use based on a basic understanding of their infant’s circadian rhythms that may help everyone get more and better sleep with a young baby in the family. I will briefly explain and discuss what I thought were the most interesting and helpful parts of her talk.

Circadian rhythms are cycles that our bodies repeat. Briana gave the example of a swing going back and forth to illustrate the concept. Some of the rhythms in our bodies are on short periods, like a swing on a short chain that goes back and forth quickly. These are called ultradian cycles. These are rhythms that take shorter than a day and include things like heart rate and appetite. Our bodies have circadian cycles that are longer and take a 24 hour day to complete. Examples of these include our sleep-wake cycles and our basal body temperature which varies over the course of the day. There are also longer cycles called infradian cycles which take much longer than a day. An example of this in the human body is menstrual cycles.

When describing how our sleep-wake cycles work, Briana explained in great detail how many biological factors in our bodies cycle throughout a 24 hour day. Our hormones including melatonin, cortisol, epinephrine, thyroid, and insulin all contribute to this cycling which controls not only our sleep-wake cycles, but also our cognitive performance as well as many biological processes.

She went on to explain how these processes need a nudge from outside influences to stay on track. She described an experiment where people were put in an environment with no light for an extended period of time and their bodies began to cycle on a 24.5 hour day, rather than 24 hours. The outside influences that keep our bodies’ circadian rhythms on track are called “Zeitgeber,” German for “time-giver.” Light from the sun and the darkness when it sets, exercise, noise, social interactions, and perhaps, she suggests, breastmilk, are all Zeitgeber, things that keep our circadian rhythms cycling with the 24 hour day.

There are also things that can interfere with our circadian rhythms including things like shift work, jet lag, lithium, alcohol, antidepressant drugs, age and perhaps even some kinds of food. In particular artificial light at night influences the part of our brain that produces melatonin and causes it to slow production. Briana explained that red lights (such as astronomers, pilots, sailors and others who want to preserve their night vision) do not activate that part of the brain and may be a helpful way to minimize the disruption to circadian rhythms for people, like breastfeeding mothers of young babies, who must be awake periodically during the night.

When our circadian rhythms are disrupted for long periods our health can suffer. Depression, mental illness and perhaps even ADHD can be caused by disrupted circadian rhythms. Many studies have found that people who do shift work on a regular basis often suffer negative health consequences including cancer, hypertension, cardiovascular disease, rheumatoid arthritis, diabetes and metabolic syndrome.

While still in the womb, infants experience day-night cycles, as well as the influence of their mother’s melatonin and other hormones. Once babies are born, they don’t produce the hormones needed to direct their own circadian rhythms for approximately the first 3 months of life. Then gradually their bodies begin to produce their own melatonin and cortisol cycles, as well as other biological rhythms.

So now that we know that young babies don’t have their own circadian rhythms, what can we learn from this information to help us make nights easier for families with young babies?

Briana Tilman described in great detail how the hormones such as melatonin and the proteins that are the building blocks of other hormones are present in breastmilk in varying levels throughout the day and night. This suggests that breastmilk helps influence babies’ sleep-wake cycles and helps bring them into their mother’s circadian rhythm. Skin-to-skin contact has also been shown to improve infant’s sleep-wake cycles and bring them more in line with their mother’s.

She also suggests that mothers who are mostly or exclusively expressing breastmilk for their infants may want to label their milk with the time of day it was expressed (at least morning, afternoon or night) and then give the breastmilk at the same time of day it was expressed.

Briana also noted that infant formula doesn’t contain any melatonin and mothers who are exclusively formula feeding may want to consider asking their pediatricians about supplementing with melatonin.

Another thing families can try that can’t hurt and might help everyone get more sleep is to use red light bulbs, rather than regular light bulbs, when getting up to tend to an infant at night. The red light is less likely to cause the parents’ melatonin production to be disrupted, and may also keep the atmosphere of the room more calm and sleepy.

As mothers who have been there know, the early months with a baby are difficult and physically exhausting, but they are also over very quickly. Along with the recommendations above, patience, support from family and friends, and knowing that before long your baby will be off to kindergarten can help mothers and families navigate nights with a newborn.

- Jessica Barton MA, IBCLC

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