Light Exposure in Pregnancy

November 7, 2015 at 4:48 am

I don’t have a lot of tasks in my morning routine. Get up. Use the bathroom. Drink water. Go into the backyard. Sit in the sunlight. The rest of the morning varies from day to day, but these first five items happen almost without fail.

Some time in the last few weeks, as I basked in the mercifully-cooler-November morning AZ sunshine, with my shirt pulled up above my belly as usual to maximize the skin exposure for vitamin d, I started thinking about how easily light travels through the skin. This is a fact most children given a flashlight are delighted to discover. Earlier today, one of my kids shouted, “Look, Mom, my finger is red,” holding a light behind her fingertip. I’ve noticed that the baby in my womb, if she hadn’t been “awake” yet, usually wakes up and starts wiggling and kicking once I’m outside with my belly in the sun. So I’ve been wondering… what, if any, effect does my daily sun routine have on my baby?


Fetal Eye Development

So I asked Google. Most of what I found centered around one particular study published in the journal Nature in January of 2013. The basic finding was… yes, fetal light exposure does have an impact. Here’s a quote:

The researchers in the current study revealed that the activation of the newly labeled light-response pathway must occur during pregnancy in order to achieve the precisely planned program that creates a normal eye. They point out that it is crucial for the right number of photons to reach the mother’s body by late term pregnancy, or for a mouse pregnancy, roughly 16 days.

Additionally, the scientists saw that photons of light trigger a protein called melanopsin inside the fetus, not the mother, to aid in the beginning of healthy blood vessel and retinal neuron development in the eye (Source).

Interesting. Hopefully this means my baby will have excellent eye health.

Fetal Melatonin Exposure

The other important fact I discovered has more to do with evening light exposure during pregnancy. When pregnant women are exposed to artificial light at night (when it should be dark) their melatonin levels will diminish. This is harmful not only for the health of the mother but also for the health of the baby. The pineal glands of fetuses don’t produce very much melatonin on their own. They rely on their mother’s melatonin, which crosses the placenta. Medical Daily explains:

If the fetus does not get the proper amount of melatonin from their mother, their biological clock can also become confused. This has been linked to behavioral problems such as attention deficit hyperactivity disorder (ADHD) or autism in young children (Source).

All women should be careful to avoid artificial light at night, in fact. There is an “undeniable link between night workers and the increased risk of developing breast cancer” (Source). I’ve previously written about melatonin’s positive impact in childbirth and the importance of protecting ourselves from artificial night-time light, particularly when trying to conceive. So it is not really surprising to me that, once again, melatonin would have a powerful impact in another physiological aspect of pregnancy and birth.

For the past several years we have done what we could to make our bedroom(s) as dark as possible at night. Having efficient window shades, using thick light-blocking drapes, and covering bright alarm clocks have all made a big difference. But I know I need to work on minimizing artificial light (especially from computers/screens) before bedtime. My sleep always takes a hit when I’m on the computer right before bed.

Boosting Melatonin Levels

All this information has me feeling motivated to do what I can to optimize my night-time melatonin levels. I already know some of the best ways to do that, so it’s just a matter of being more diligent with them.

Some tips for healthy melatonin production:

  1. Harness day-time light. My morning light ritual is, actually, one great way to help improve night-time melatonin levels. Part of getting your body’s systems and hormones into a healthy rhythm includes utilizing the normal rise and fall of light exposure. This is true for children and infants as well. One study found, “Babies who slept well at night were exposed to significantly more light in the early afternoon period” (source).
  2. Meditate. Research has shown (and my own experience gives more anecdotal evidence) that meditation can significantly benefit melatonin levels. One study’s abstract states: “Facilitation of higher physiological melatonin levels at appropriate times of day might be one avenue through which the claimed health promoting effects of meditation occur.”
  3. Boost magnesium. Magnesium supplementation can bring about “statistically significant increases” in melatonin levels (as well as sleep duration and quality). The study in the previous sentence used 500 mg of oral magnesium, but I prefer to use topical magnesium for lots of reasons you can read more about HERE.
  4. Eat more pineapple. I eat a lot of pineapple myself, but until tonight I had no idea that eating pineapple could boost serum melatonin levels. Cool. The same is true of bananas and oranges. “The highest serum melatonin concentration was observed at 120 min after fruit consumption,” so it sounds like a pineapple smoothie two hours before bed is a great idea (Source).