How Light Affects Your Child's Sleep


Today we’re talking all about something that’s crucial to sleep: light.

Light is an extremely important part of our circadian rhythms, which in turn play a huge role in our sleep. This is even more true for babies and children.

This is why the Kulala method has such an emphasis on light.

Let’s get into that in a little more detail.

Light and Your Eyes

Our eyes are marvelous things. We can go seamlessly from shade to sunshine, from moonlight to full sunlight, and our eyes will adjust rapidly.

What we don't know, or even feel, is just how different the actual light intensities are in those different environments.

What may seem to us to be just a little bit brighter, or a little bit darker, can actually be a thousand times brighter or darker. Our eyes just can’t perceive that.

Have you ever put on your makeup or tweezed your eyebrows in the bathroom, in artificial light, only to catch your reflection later in direct or indirect sunlight, and noticed how different everything looks? Little hairs you couldn’t see before are suddenly very clear, and that eyeshadow that looked fine in the bathroom light looks way too heavy in the daylight.

We completely underestimate the differences in light exposures around us because it’s just not visible to the naked eye. That's why it's hard to attribute any importance to light exposure on our sleep at all—because we simply can't feel it.

While we can't consciously feel it, our eyes and brain are actually supremely sensitive to light. They measure it precisely. Even a little bit of light in the morning is enough to tell our body that it's wake-up time, and even a little bit of light at night can keep us up for hours. ⁠

What Do Different Types of Light Have To Do With Sleep?

Light is made up of different wavelengths that correspond to different colors. In the morning, sunlight has a higher proportion of blue light, signaling our bodies it’s time to wake up. While in the evening, the blue light decreases as the amount of red light rises (which is why sunsets have pink, orange, or red light). This decrease in blue light and increase in red light tells our bodies it’s time to get ready for sleep.

This is how circadian rhythm works.

We don’t know exactly when circadian rhythm develops in utero, but we do know it exists by the third trimester. Meaning babies are born with a circadian rhythm already intact!

So it stands to reason that working with your baby’s circadian rhythm, rather than in opposition to it, is the way to help them get the most sleep.

How do you do that?

By regulating the light around them.

Melatonin, the hormone released at night that regulates our sleep, has been shown to decrease in the presence of blue light. Artificial lights, like incandescent lightbulbs and the light from TVs, tablets, and smartphones, may look yellow or white to our eyes—but they all release some amount of blue light. Even candlelight has a small amount of blue light in it!

So it stands to reason to help us sleep, we need to eliminate blue light from our sleep environments.

sleeping baby

How Does Light Affect Your Child’s Sleep?

Science has shown that young children are even more affected by the disruptions caused by blue light, especially when it comes to sleep.

Why? Scientists hypothesize it’s the fact that the lenses in their eyes, which transmit light from the outside world to the backs of the eyes, are clearer than in adults. These lenses become more cloudy with age.

Whatever the case, the studies are clear: when children are exposed to high levels of blue light at night, their melatonin levels—which normally rise after sunset—are erased from their bodies. This makes it much harder for them to get to sleep—and much harder for them to stay asleep.

That’s why it’s so important to eliminate blue light from their sleep environments.

There are a few ways to do this.

Invest in good blackout shades

You need blackout shades for naps, obviously, as naps generally take place during the day when the sun is out.

But blackout shades are also helpful for mornings, if you want your child’s wakeup time to be closer to, say, 8 AM than 5 AM. Blackout shades will help keep out early morning sunlight that could signal to your child it’s time to wake up. In the same vein, if you want your child to go to bed earlier in the summer, blackout shades help eliminate those lingering rays of sunlight.

Which blackout shades should you buy?

There are several options.

Amazon makes some basic, affordable, portable shades that we love. For a more permanent, albeit slightly pricier option, Home Depot makes custom-cut blackout shades. And the New York Times recently did a great roundup of several more of the best shades on the market; check it out and find the right ones for you.

Not home? Not a problem! When you're on the go, Snoozeshade and Slumberpod are both great options for getting your baby that much-needed blackout sleep.

Turn off all screens before bedtime

This is good advice for everyone, children and adults! For us adults, turning off screens has the added benefit of eliminating stimulating content like the news, or anything that will make us excited or upset. But the most important component of eliminating screens is getting our eyes away from that blue light. Smart phones and tablets that aren’t on Night Mode emit a large amount of blue light.

And as we said before, eliminating blue light is even more important for children, as they’re so sensitive to it. In fact, in 2015, a meta-analysis of 67 studies aiming to test the effects of screens on children came to a definitive conclusion: Ninety percent of the studies found a correlation between evening screen time and poor sleep!

Use a red light lamp in the bedroom

While the incandescent bulbs in the lamps in your child’s bedroom may feel minimally invasive when it comes to light, the truth is all lightbulbs have a little blue light in them—except red light lamps.

Red light has been used in labs for years in order to allow scientists to work with their subjects, be they flies or another kind of insect or animal, without disrupting their sleep. Unlike blue light, red light does not disrupt melatonin production, which means it doesn’t disturb our circadian rhythms, or your child’s sleep.

Keeping a red light in your child’s bedroom means you’ll have eliminated all blue light well before bedtime. It has the added bonus that if you need to turn the light on at some point during the night, you’ll be at a lower risk of waking them up. And if your child does wake up, they’ll be able to get back to sleep more easily, having only the red light on. There will be nothing in the room signaling to their bodies it’s time to wake up.

You can easily find red light bulbs in any hardware store and simply replace your existing light bulbs in your child's bedroom lamps with them. You can also buy a lamp made specifically for this purpose.

The Kulala Baby Sleep Lamp was designed with circadian rhythm in mind. Keep it in your nursery for those first few months when baby will be waking at night—it will help them get to sleep more easily after night feedings and diaper changes. And keep it in their bedroom once they get older. Even once they’re sleeping through the night, the occasional nighttime disruption will happen. Plus if you turn off other lights and keep only the red light on for storytime, it will help them get sleepier faster.

Bonus: it’s a stylish lamp that looks great in any bedroom, child’s or adult’s!

The bottom line is:

You are the one who should be establishing your child’s sleep schedule—not the sun!

Children often need more sleep than there are hours of total darkness. And of course depending on where you live—say, a Nordic country where the sun only goes down for a few hours per night in the summertime—you may need to employ blackout shades and red light more often than those living closer to the equator. Your needs will depend on the seasons as well, as more light will leak into your child’s room in the summer than in the winter.

But the good news is with blackout shades and red light—not to mention eliminating blue light from screens and other light sources—it doesn’t matter where you live or what time of year it is. You’ll have created the perfect sleep environment, light-wise, enabling your child to get the right amount of sleep for their age.

baby sleeping in car

My baby falls asleep in the car or stroller during the day. Does this mean she’s not as sensitive to light?

Tell us if you’ve heard this one before: All babies are different. What works for one baby may not work for another.

It is certainly true that all babies are different! And that some babies will be more sensitive to light than others.

But what doesn’t change from baby to baby (or from human to human) is how circadian rhythm and melatonin work. While some babies may fall asleep and stay asleep more easily in daylight, all babies can benefit from eliminating blue light from their sleep environments. 

In conclusion:

By using the power of light to our advantage, we can naturally tap into our children’s circadian rhythm. This makes getting them to go to sleep at night, as well as getting them to stay asleep during the night, much easier.


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