Nurturing baby’s solar callus

Benefits of sunlight for babies, how to build a newborn solar callus, and why to question sunscreen use on babies

How much sunlight can a baby’s delicate skin handle?

After my first baby was born, I stayed in bed for several days. Every night, my husband would turn off the breaker in our bedroom. This cut down on the electrical frequencies while we slept. It was late springtime, so we had nice long sunsets and dawns, plus, the moon was bright. I still remember the first time we brought our eldest daughter outdoors: it was to watch a lunar eclipse!

As the summer went on, we didn’t have a specific daylight strategy. But the weather was nice and our home was small. Years past my grandmother had taught me that the skin is an absorptive organ. As such, you don’t put anything on your skin you wouldn’t put in your mouth. Thanks to Grandma’s guidance, I have never kept sunscreen in the house.

I honestly didn’t think much about protecting my baby from the sun until I had a guest exclaim over my baby’s beautiful, sun-kissed skin. “I want a tan baby!” she said. “My babies were always pasty white.”

“But aren’t you worried about her getting skin damage?” she went on to ask.

We were outside visiting in the yard, thanks to aforementioned tiny house. I wasn’t worried then, and I continue to trust my ability to intuit how much sun my babies can handle.

The more I learn, the more I am sure it is wise to enjoy the sunlight with our babies.

Sunlight supports infant development

Here are references for just a few of the really important reasons to bring baby into the sunlight:

• bilirubin metabolism in babies with jaundice¹

• retinal development - first 6 mos especially important²

• motor development - especially relevant for infants of mothers with perinatal depression³

• reduces risk of eczema and atopic dermatitis⁴

• likely supports minipuberty⁵ (via sunlight’s modulation of the endocrine system⁶)

• sunlight-exposed babies can have better Vitamin D status than their mothers (especially after 3 months of age)⁷

and more!

Yet there’s a big lobby warning against letting baby in the sunshine. And it’s true that babies are more sensitive to the sun than adults. Today, I’m interested in sharing a view that respects both opinions of solar exposure for babies. Since caution is where much of mainstream culture is currently at, I thought it would make sense to start there.

5 differences in newborn skin that affect sunlight tolerance

Newborn skin is different than mature skin in key ways that affect a baby’s ability to process and tolerate sunshine. It actually seems newborn skin is designed to absorb sunlight faster—perhaps indicating a greater need to absorb more faster, or to capitalize on the short windows of opportunity they get. Particularly, the amount of melanin and overall permeability in newborn skin are very different than adult skin⁸. Here are some key differences:

1. less melanin (UV light may penetrate deeper)

2. less thermoregulation (can get too hot or too cold quicker)

3. more permeable to water (can hydrate and dehydrate faster)

4. more permeable to chemicals (sunscreen⁹ and other topical products contraindicated)

5. more vellus hair¹⁰ (may absorb UV light at a greater rate)

What all this means is that a baby reaches its sunlight limit faster than an adult. Since babies are more sensitive, caregivers need to practice caution. This is especially true for babies born late-spring through early-autumn, when everyone else will have a significant solar callus and be more acclimated to the sun already. Interestingly, a study done on Vitamin D status in mothers and infants in Nepal found that babies could have a higher level than their mothers. The authors speculated that it was from time spent outdoors.

In my experience, most people are very attuned to the needs of babies. Babies are also very good at communicating when they are uncomfortable!

How much sunlight is safe for babies?

It’s hard to find a recommendation for how much sun anyone, but especially a baby, *should* get. Here’s one recommendation I was able to find from a study done in Australia (cited in footnotes).

• 1-2+ hours/day in up to 30 minute increments for first 2 months

• mother chooses time of day and duration with goal of 7-14 hours/week

This investigation was focused on the association of Vitamin D status to eczema development in children. According to the authors, benefits attributed to Vitamin D may actually be from UV exposure based on the fact that Vitamin D supplementation alone did not affect eczema. Rather, the best outcomes were in the top sunlight exposure group!

This 14 hour/week target is slightly less than the target of 3 hours per week recommended in most literature for older children (see 1000hoursoutside.com for more info on this). This Australia study didn’t actually include a group striving for more than 2 hours per day. So, we don’t actually know that is *unsafe* for a baby to have more than 2 hours/day; it just hasn’t been tested by science so far. Logically, spending more than 2 hours per day outside was probably common for babies in the past.

What if baby gets a sunburn?

If baby gets a sunburn, the more immediate concerns may be to ensure baby hasn’t gotten too hot or too dehydrated. Practicing skin-to-skin helps them thermoregulate, and breastfeeding helps them hydrate. Photobiomodulation (PBM), which counterintuitively is most safely and easily done with the sun, speeds healing time. PBM can be done with the sun whenever shadows are longer than the objects that cast them.

With long shadows, there is no UV, only infrared. The infrared, as I shared in the previous post Quantum Strategies for Morning Sickness, charges the collagen and delivers anti-inflammatory electrons throughout the body (including to the skin)—an effect that can be further maximized by earthing with bare feet on the ground. You don’t have to put your baby on the ground because if you are earthing, anywhere you are skin-to-skin with your baby will then transfer the electrons to them.

So, in the evening and morning, you can help baby heal from excess sunlight exposure by absorbing electrons from the earth and the sun. It is especially effective when the weather is cool. This type of PBM solar exposure has also been shown to give protection of up to SPF 15 in adults! Careful and deliberate use of morning, afternoon, and evening sunlight support the complementary purposes of PBM and vitamin D production (not to mention setting both of your circadian rhythms!).

Anecdotally, topical breastmilk and fresh aloe vera (from a plant, not a product mixed with preservatives) can help soothe the pain of sunburn, too.

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1. Horn, D., Ehret, D., Gautham, K. S., & Soll, R. (2021). Sunlight for the prevention and treatment of hyperbilirubinemia in term and late preterm neonates. The Cochrane database of systematic reviews, 7(7), CD013277. https://doi.org/10.1002/14651858.CD013277.pub2

2. Orjuela-Grimm, M., Carreño, S. B., Liu, X., Ruiz, A., Medina, P., Ramirez Ortiz, M. A., Rendon, J. R., Molina, N. C. L., Pinilla, H., Hinojosa, D., Rodriguez, L., Connor, A. O., Rodriguez, F. M., Castañeda, M. V. P., & Cabrera-Muñoz, L. (2021). Sunlight exposure in infancy decreases risk of sporadic retinoblastoma, extent of intraocular disease. Cancer reports (Hoboken, N.J.), 4(6), e1409. https://doi.org/10.1002/cnr2.1409

3. Zhang, H., Liu, S., Si, Y., Zhang, S., Tian, Y., Liu, Y., Li, H., & Zhu, Z. (2019). Natural sunlight plus vitamin D supplementation ameliorate delayed early motor development in newborn infants from maternal perinatal depression. Journal of affective disorders, 257, 241–249. https://doi.org/10.1016/j.jad.2019.07.010

4. Rueter, K., Jones, A. P., Siafarikas, A., Lim, E. M., Bear, N., Noakes, P. S., Prescott, S. L., & Palmer, D. J. (2019). Direct infant UV light exposure is associated with eczema and immune development. The Journal of allergy and clinical immunology, 143(3), 1012–1020.e2. https://doi.org/10.1016/j.jaci.2018.08.037

5. Bizzarri, C., & Cappa, M. (2020). Ontogeny of Hypothalamus-Pituitary Gonadal Axis and Minipuberty: An Ongoing Debate?. Frontiers in endocrinology, 11, 187. https://doi.org/10.3389/fendo.2020.00187

6. Slominski, A. T., Zmijewski, M. A., Plonka, P. M., Szaflarski, J. P., & Paus, R. (2018). How UV Light Touches the Brain and Endocrine System Through Skin, and Why. Endocrinology, 159(5), 1992–2007. https://doi.org/10.1210/en.2017-03230

7. Haugen, J., Ulak, M., Chandyo, R. K., Henjum, S., Thorne-Lyman, A. L., Ueland, P. M., Midtun, Ø., Shrestha, P. S., & Strand, T. A. (2016). Low Prevalence of Vitamin D Insufficiency among Nepalese Infants Despite High Prevalence of Vitamin D Insufficiency among Their Mothers. Nutrients, 8(12), 825. https://doi.org/10.3390/nu8120825

8. Oranges, T., Dini, V., & Romanelli, M. (2015). Skin Physiology of the Neonate and Infant: Clinical Implications. Advances in wound care, 4(10), 587–595. https://doi.org/10.1089/wound.2015.0642

9. Gabros S, Nessel TA, Zito PM. Sunscreens and Photoprotection. [Updated 2023 Jul 17]. In: StatPearls [Internet]. Treasure Island (FL): StatPearls Publishing; 2023 Jan-. Available from: https://www.ncbi.nlm.nih.gov/books/NBK537164/

10. Huang, X., Protheroe, M. D., Al-Jumaily, A. M., Paul, S. P., Chalmers, A. N., Wang, S., Diwu, J., & Liu, W. (2019). Contribution of Human Hair in Solar UV Transmission in Skin: Implications for Melanoma Development. Annals of biomedical engineering, 47(12), 2372–2383. https://doi.org/10.1007/s10439-019-02315-z