Melatonin and Labor

Part 1 (get ready to geek out even more in Part 2) and Part 3 of the series.

Oxytocin tends to get all the credit for labor and birth, but recent exciting research is finally putting melatonin in the spotlight - and for good reason. This is a very comprehensive dive into melatonin so pace yourself!

Dim lighting! Dim lighting! Why is dim lighting recommended by everyone who knows anything about labor and birth (other than hospitals...?).*** Why are well informed doulas recommending sunglasses for labor (in fact blueblockers are more effective, not sunglasses)? It’s not just to promote relaxation and intimacy but to trigger specific cellular activities that can help labor progress, reduce pain and promote recovery.

Let’s jump into some helpful info on this super hero hormone. Melatonin is one of the most powerful antioxidants in the body. What the heck are they anti-what? During all of the trillions of processes our cells get up to during the day and how our cells process energy, oxidative stress molecules get left behind and can be very harmful to us. A by-product of making energy is oxidative stress. This is a ‘stress’ we can’t avoid. Oxidative stress molecules can attack healthy cells in the body. These special molecules (ROS - reactive oxygen species) are associated with less optimal health, more inflammation, cancer and diabetes.

Melatonin is a hormone that our body naturally produces in the pineal gland and the placenta during pregnancy. This is the melatonin that is circulating in your blood. It's often referred to as the "hormone of darkness" because it helps regulate our sleep-wake cycles. That’s part of the reason why labor starts at night for so many. In the evening time, melatonin starts to reduce brain activity so we sleep more soundly and labor can do it’s thing. But it also plays a crucial role in fertility, labor and birth as well as overall health.

But there’s another form of melatonin that’s made in our mitochondria (our little energy producing cells) and have a very different function - to help our cells work optimally and clean up all of those harmful cells.

Night Time Melatonin for Healthy Sleep

In a nutshell - at night-time the light outside dims sending a message to a specific part of the brain (SCN). When the light hits the retina in your eye special cells in the bottom of your eye (ipRGCs) tell your pineal gland to release melatonin then these little chemical messengers go around the body telling all of your cells to get ready for bed. Sun goes down - melatonin goes up (unless we interrupt it with a bright light…or our phones…TV…etc). But those ipRGCs also branch off into areas of the brain associated with mood - including the amygdala (remember fight/flight?).

Day Time Melatonin for Healthy Metabolism

In the daytime, it’s bright so the pineal gland stops melatonin production. We are going about our day multitasking a mile a minute, and with so many cellular processes our mitochondria desperately needs energy AND a helper to stop these tiny engines overheating. So the mitochondria has to make it’s own energy. But how does the mitochondria get this melatonin? Cellular reactions within the mitochondria and sunlight. Specifically near infra red light (an invisible part of the light spectrum). When we are out in the sun NIR directly activates melatonin by penetrating the skin, so melatonin is also available to our cells during the day to mop up the damaged cells that can affect our health. Are you still with me?

Why is This Important?

It’s estimated that we spend more than 90% of our day indoors, and the primary way to get that important daytime melatonin is from sunlight (NIR specifically). Over 54% of the sun’s radiation is infrared radiation. So how else can you help your body if you’re not in the sun? A home light unit that includes red and NIR.

Studies have shown that melatonin levels rise as the body prepares for labor. This hormone's primary job during labor is to make the birth process smoother. Melatonin’s properties include pain reduction, regulation of mitochondrial function (how much energy your cells have - definitely important for labor), anti-inflammatory, anti-oxidative and neuro-protective effects, sleep and immune enhancement. Notably, melatonin also teams up with oxytocin to enhance the efficiency of labor. Melatonin passes through the placenta, reaching the baby's blood, and helps protect baby from cell damage due to its antioxidant properties.

Wai Man G.C. et al., 2017 shows the correlation between the circadian clock and the immune system. Melatonin also regulates the distribution of immune cells throughout the body. (Lymphocyte proliferation, enhancing phagocytosis and stimulating cytokine production - specialist cells that go to injury sites and reduce infection). Therefore, in pregnancy, melatonin can help suppress various inflammatory complications, including preterm labor, gestational diabetes, and preeclampsia.

Note: Babies born by planned cesarean aren’t born with physiologic melatonin levels for long-term health. Some studies are exploring the impact of melatonin supplements on premature babies.

Melatonin as a Method of Induction?

In 2020 researchers began a randomized, double-blind study (MILO) investigating if there are differences in cesarean rates if one group of women are given a melatonin supplement in the early active phase of an induction, compared to a standard induction with Pitocin. The results have yet to be published.

Melatonin and Preterm Labor

So here's where it gets really interesting. We're in an incredible moment in the history of medicine because scientists have discovered that specific wavelengths of artificial light or medication can either enhance melatonin production or inhibit it.

At least two studies have investigated the impact of using specific wavelengths of light to slow down the frequency of contractions. Women were randomized to have their uterine activity monitored at night after having exposure to a lamp with a 507nm wavelength (blue/green light) - 1 meter away. On average, uterine contractions increased between 1.4 and 2.1 contractions per 30 minutes for every 10 pg/mL*h increase in melatonin concentration.

Melatonin and Pregnancy Complications

Women with Gestational Diabetes tend to have low melatonin levels. Low levels are also seen in pre-eclamptic women.

Giving birth by real candlelight is lovely but LED lights are popular, brighter, cheaper, more durable, and safer. However, some researchers are concerned because the bright LED lights in the birth environment may hinder melatonin production and its effect on oxytocin production. Ready to geek out again? Scientists have identified wavelengths of light that either increase melatonin production in the body - or reduce it in the case of preterm labor.

So, as you can see, the science of photobiomodulation (red light therapy) is just starting to make an impact on women’s health - especially pregnancy. The science of light therapy for fertility is well-established in Japan and Scandinavia.

Over the coming months I’ll be sharing more information on the scientific use of specific light wavelengths in pregnancy, birth and postpartum and how you can use this therapy safely at home and at the hospital.

***If you’ve ever heard of moms being advised to wear big ‘Bono’ sunglasses as you enter the hospital, it’s to reduce the impact of all of that bright light on your labor and reduce the risk of your labor stalling. However sunglasses won’t completely block blue light - blueblocker glasses are likely to be more effective ***