The Science Behind Blackout Curtains: Do They Really Improve Baby Sleep?

On the internet, you’ll see a lot of variable information about blackout curtains and infant sleep. That’s just the nature of bias and wide differences in how people define what matters for sleep. Some folks swear by blackout curtains as a magic fix. Others treat them as optional nursery decor. So what’s the real answer?

In this blog, I’m going to break down the science of light and sleep, explain why darkness matters for babies, share evidence based recommendations, and tell you what many parents (including those I work with) actually experience. I’ll also link to other relevant Heaven Sent Sleep content so you can go deeper on related topics. And yes, I’ll include my honest review of OtterSpace blackout curtains with my affiliate discount code (because transparency matters).

Let’s get into it.

Why Light Matters So Much for Sleep

Sleep isn’t just about being tired. It’s a biological process controlled by a 24-hour internal clock called the circadian rhythm. Light is one of the biggest environmental cues that tells the brain when it’s time to be awake or asleep. When light hits the retina, especially in the blue spectrum, it signals to the brain that it’s daytime, which suppresses melatonin production, the hormone that helps us feel sleepy. (ParentData by Emily Oster)

In infants, circadian rhythms are still developing, but they respond to light from very early on. Studies show that aligning a baby’s environment with a consistent light/dark pattern helps support more predictable sleep-wake cycles. The presence or absence of light directly influences hormone rhythms and the body’s internal clock. (PMC)

One observational study found that infants in dark sleep environments had more consolidated nighttime sleep compared with less dark environments, suggesting a dark room supports longer sleep duration even in early months. (PMC)

In practical terms, that means light exposure at bedtime or early morning can affect how easily your baby falls asleep and how well they stay asleep.

Research on Darkness and Baby Sleep

You’ll find a few points consistently supported by research and expert opinion on this topic:

1. Darkness Encourages Melatonin Production

Multiple sources note that darkness, particularly at night and during naps, supports melatonin production which signals to the brain that it’s time to wind down. Light, even indirect street lamps or early sunshine, can suppress melatonin and signal the brain that it’s time to wake up. (ParentData by Emily Oster)

2. A Darkened Room Reduces Stimuli

Babies are very sensitive to environmental cues. Light isn’t just visual; it triggers wake signals in the brain. A dark room lowers the chance of early waking and mid-sleep disruptions triggered by light changes. Reports from child sleep consultants and pediatric sources routinely recommend a dark sleep environment for this reason.

3. Dark Rooms Help Nap Entrainment Too

Good nighttime sleep and good naps go hand in hand. During the long days of summer, or if the nursery faces bright sunlight, blackout curtains help prevent sunlight from creeping in and interrupting sleep. That means deeper, longer naps and smoother transitions between day sleep and night sleep.

So while blackout curtains aren’t the only thing that matters for sleep, light control is one of the environmental factors that does make a measurable difference.

And if you’re curious about specific products, I personally tested OtterSpace blackout curtains in our home. My full review is here, but the short version is:

“We’ve had the OtterSpace Blackout Curtains up since July and have zero complaints. They’re super easy to install, portable for travel, and they truly block out all light. You can use your own curtains or bundle the blackout layer with theirs. Installation with magnets or Command strips is straightforward, and whenever you want natural light you just detach the blackout layer. If you’re serious about a dark sleep environment, these are a great option.” (Heaven Sent Sleep)

I also have a 10% off code: HEAVENSENTSLEEP10 if you want to try them for your home without paying full price. (Affiliate disclosure: using that code supports the blog at no extra cost to you, and helps me continue sharing evidence based, response based sleep strategies.)

How to Pair Blackout Curtains With Good Sleep Habits

Blackout curtains aren’t a magic fix. Light control is just one piece of a sleep ecosystem that includes timing, routines, sleep associations, and daytime nap structure, all things I talk about often here on the blog.

A few relevant posts you might want to read next:

• How to Create the Perfect Sleepy Nursery — includes lighting, noise, and overall environment tips.

• Wake Windows vs. Sleep Schedules — helps you match naps and bedtime to your baby’s biological needs.

• When Do Babies Sleep Through the Night? — realistic milestones and how environment plays a role.

Implementing blackout curtains works best when you combine them with predictable routines and age-appropriate awake windows. Darkness tells the brain it’s time to sleep, but routines give the brain context for what comes next.

Choosing the Right Blackout Solution

Not all blackout curtains are created equal. Some are single-layer and only filter light. Others, like the OtterSpace option I reviewed, block nearly all external light and are versatile for travel or rentals. (Heaven Sent Sleep)

Here’s what to consider when choosing blackout curtains:

• Opacity level — choose true blackout if you struggle with early morning light.

• Ease of installation — magnetic systems or removable layers help if you travel or move rooms.

• Versatility — can you use them with your existing curtains? Are they reusable?

• Safety and materials — make sure hardware and cords are safe around small children.

Final Thoughts

So do blackout curtains improve baby sleep? Based on research and real parent experience, yes— they help create an environment that supports better sleep quality and consistency. Darkness cues the brain to produce melatonin, reduces visual stimuli, and helps sleep routines feel more predictable.

That said, they’re just one tool in your sleep toolbox. Pair them with reliable routines and age appropriate schedules for the best results.

If you’re curious about whether blackout curtains make sense for your family or want help building a full sleep plan around them, I’d love to support you in that journey.