When I wrote "What I'd do if my baby had eczema", point three was about light. It was the shortest section and it's the one I get the most questions about, so here's the longer version.
Babies aren't born with a working body clock. They build one, over the first couple of months, and light is the main thing they build it out of. It matters for skin specifically, because skin loses water fastest at night. That's measurable and it's why itch often gets worse after dark and why kids scratch themselves raw at 2am while sleeping. Sleep is also when repair happens. So a kid whose clock is scrambled is a kid whose skin is trying to rebuild during the wrong hours.
None of what follows costs anything. You don't need a lamp, an app, or a protocol. Do the first one and skip the rest if that's all you've got today.
1. Morning light is a priority for them
If you only do one thing, do this. Get them outside within an hour or so of waking. Five minutes is enough. Fifteen is better. (It will be good for you too).
It doesn't have to be sunny. It doesn't have to be direct sun — shade outdoors is still ten to a hundred times brighter than your kitchen. What matters is being outside, because window glass cuts most of the signal.
This is the input that tells a body when the day starts. Everything downstream — melatonin at night, cortisol in the morning, appetite, mood, sleep — is set by it.
Set yourself up for success. If you're feeling energetic, make it a walk. If last night was a rough one, get a snuggly chair and blankets. If it's the winter, sit in front of the open window. Make it work for you.
2. Daytime is about brightness, not sun
Kids need a bright day. Bright ambient light during the day is what makes the contrast with darkness at night meaningful.
For babies under six months: we don't do sunscreen, we do shade. Under a tree, under a stroller canopy, under a hat. They're still getting the signal.
For older kids: outside, hats, shade in the middle of the day, and don't let them burn. That's it.
3. Shade near green things is not nothing
Leaves and grass reflect a lot of light we can't see, in the near-infrared range. Sitting in dappled shade under a tree is a different light environment than sitting under a patio umbrella, and the thinking is that this deeper-penetrating light supports repair at a cellular level.
4. Evening is where the leverage is
After the sun goes down: overhead lights off, lamps on, screens away or dimmed and warmed. Candles if you like them. If you've got a kid who melts down at bedtime and scratches all night, a dim hour before bed does more than most things you can buy.
Blue light in the evening pushes the clock later. In a small body with a clock that isn't finished yet, that lands harder than it does in you.
5. Dark rooms
Dark, properly dark, for sleep. If you need something to see by for feeds and changes, make it dim and red rather than white or blue. Turn your phone to red if you're on it for evening feeds. Get a Daylight computer. I think they make a Kindle with an orange light. Black out your/their windows. I have done tinfoil and I have taped material to my walls. The goal for me wasn't aesthetic, it was blackout on a budget.
6. If you're in a cold climate
I'm in Calgary and part of the year in Montana, so this is my actual life.
- You cannot make vitamin D here in winter. At this latitude there's essentially no UVB from late October to late March due to the angle. Winter sun is still worth going out for — it still sets the clock, lots of UVA, lots of free red light therapy — but it is not doing anything for vitamin D. (I never did drops for the kids and none of us supplement it. We are white, we have evolved to thrive in the north. Cold is the key here.)
- Grey days still count. An overcast winter morning outside is still far brighter than indoors. Go anyway.
- Get the light early, because there isn't much of it. In December, "morning light" and "the only light" are the same thing.
- Indoor brightness matters more in winter. Open the blinds, sit near the window, and then contrast it hard with a dim evening.
7. If you're in a hot climate
The problem flips. You have plenty of light and the risk is heat.
- Heat and sweat are eczema triggers in their own right. A hot, sweaty baby can flare regardless of how good your light hygiene is.
- Use the early and late windows. First hour or two after sunrise, last couple before sunset. These are the good windows anyway.
- Midday is for indoors or deep shade. Not a moral failing, just sensible.
- Watch for overheating before you watch for burning. Babies dehydrate fast and don't regulate temperature well.
8. Your light matters too, if you're feeding
Breastmilk isn't a constant. Melatonin in milk rises at night and drops in the morning, and it tracks the light you've been in. So when you get your own morning light and dim your own evening, you're handing your baby a time signal in every feed.
This is the part I didn't understand with my first and it's the part that made everything easier with the other two. It's also the most self-serving advice in this post, because it means going outside in the morning is something you get to do for yourself and count as doing something for them.
9. What I don't stress about
- Naps in daylight. Fine. Bright days and dark nights, not dark everything.
- Missing a morning. It's a rhythm, not a streak.
- Perfect timing. The apps are interesting and I use one (it's called Circadian), but "outside in the morning, dim at night" gets you most of the way there without ever opening your phone.
TL;DR
- Outside within an hour of waking. Five minutes. Shade counts. Every day you can.
- Bright days.
- Trees over umbrellas when you have the choice.
- Overhead lights off after sunset. Lamps and warm light only.
- Dark room for sleep. Red bulb/reading light if you need one.
- Cold climate: still go out! Cold is good. Light is always good.
- Hot climate: early and late, and watch the heat more than the sun.
- Your own light gets passed on in your milk.
None of this replaces figuring out the detergent, the bath water, or the food. It just costs nothing and it works while you sleep, which is more than most things can say.
xo Caitlin