The Complete Guide to Blackout Windows for Better Baby Sleep

Why Parents Search for Ways to Blackout Windows

If you’ve ever wondered why your baby wakes at 5am when the sun comes up, light is often the culprit.

As parents ourselves (and the founders of Porta Fox), this is one of the most common problems we hear from families. Many nurseries look calm and cosy, but the room can actually be far brighter than it seems once the sun rises.

Even small amounts of light entering a bedroom can signal to the brain that it’s time to wake up.

Research shows that light exposure is one of the most powerful signals controlling the body’s circadian rhythm, the internal clock that regulates sleep and wake cycles.

For babies and young children, this system is still developing, which means they can be especially sensitive to light changes in their sleep environment.

This guide will walk you through:

• why darkness matters for sleep

• how to blackout different types of windows

• the best blackout solutions for nurseries

• common mistakes parents make

• practical solutions we’ve seen work for thousands of families

Why Darkness Matters for Baby Sleep

Sleep isn’t just about routines, it’s also about environmental signals. The most important signal your body uses to regulate sleep is light exposure.

Light and Melatonin

Melatonin is the hormone that helps signal to the brain that it’s time to sleep.

Research shows:

• light exposure suppresses melatonin production

• children are more sensitive to light than adults

• evening light exposure can delay sleep onset and disrupt sleep patterns

Studies have also found that consistent light-dark cycles help infants develop more stable sleep patterns and improve night-time sleep duration.

In simple terms:

Because babies are still developing their circadian rhythm, light leaks in the nursery can easily confuse those signals.

How Dark Should a Baby’s Room Be?

Many sleep experts recommend that nighttime sleep environments are very dark — sometimes described as “cave-like.”

A useful rule of thumb:

Once your eyes adjust, you should struggle to see your hand in front of you in the room.

During daytime naps, darkness can also help babies fall asleep faster by reducing visual stimulation.

Common Signs Your Nursery Might Be Too Bright

Parents often don’t realise light is affecting sleep until they notice patterns like:

• baby waking very early in the morning

• short daytime naps

• difficulty settling at bedtime

• waking when the sun rises

We hear from many parents who initially assume sleep regressions or developmental leaps are the cause, but once they improve the room darkness, sleep often improves too.

Different Ways to Blackout Windows

There are several ways to block light from entering a bedroom.

Some solutions are permanent, while others are designed for renters or travel.

Comparison of Blackout Solutions

From our experience working with thousands of parents, the biggest issue isn’t the fabric itself - it’s light gaps around the window.

That’s why solutions that attach directly to the glass often block more light.

How to Blackout Any Window (Step-by-Step)

Step 1: Measure the Window

Measure:

• width

• height

• frame depth

Always allow a small overlap around the edges to prevent light leaks.

Step 2: Choose the Right Type of Blind

Consider:

Step 3: Install the Blind

Most portable blackout blinds install using:

• suction cups

• adhesive Velcro tabs

Installation usually takes just a few minutes.

Step 4: Seal Light Gaps

Light gaps often occur:

• around window edges

• between curtains

• at the top corners

Solutions include:

• overlapping blinds slightly

• adding Velcro strips

• layering with curtains

How to Blackout Large Windows

Large windows are common in modern homes, but they can be harder to cover.

Some solutions we commonly recommend include:

1. Use Two Blinds

Many parents install two blinds side-by-side.

Slightly overlapping them helps prevent light leaks.

2. Layer Curtains with Blinds

Curtains can add an extra layer of darkness.

This combination also gives nurseries a softer, more decorative look.

3. Use Cut-to-Size Fabric Blinds

Some blackout fabrics can be trimmed to fit custom window shapes.

This creates a cleaner appearance and reduces gaps.

Blackout Solutions for Renters

Many families renting homes worry about damaging walls or window frames.

Fortunately there are several renter-friendly blackout options.

Portable blackout blinds are particularly popular with renters because they attach directly to the glass and leave no marks when removed.

Portable Blackout Blinds for Travel

Sleep routines often get disrupted while travelling.

Brighter hotel rooms, holiday homes or grandparents’ houses can make it harder for babies to sleep.

Portable blackout blinds can help recreate a familiar sleep environment.

Parents commonly use them in:

• hotels

• holiday rentals

• caravans

• family visits

Because they fold up compactly, they’re easy to pack.

Common Mistakes Parents Make When Blacking Out a Room

From our experience helping customers, these are the three most common issues we see.

Choosing blinds that are too small

Even a 1–2 cm gap can allow significant light in.

Only covering the glass

Light can enter around the frame if the blind doesn’t extend slightly past it.

Relying only on blackout curtains

While blackout curtain fabric blocks light through the material itself, light commonly leaks around the edges of the window frame. Even these small gaps can let in enough morning light to signal to a baby’s brain that it’s time to wake.

What Sleep Research Says About Light and Sleep

Sleep researchers consistently emphasise the importance of environmental light in regulating circadian rhythms.

For example:

• Light exposure influences melatonin production and sleep timing (Sleep Foundation)

• Consistent light–dark cycles help infants develop regular sleep patterns (Scientific Reports)

• Circadian rhythm signals strongly influence sleep timing in both adults and children (RACGP)

While sleep is influenced by many factors, environmental light is one of the most controllable elements of a sleep environment.

Final Thoughts: Creating a Sleep-Friendly Nursery

Every baby is different, and sleep challenges rarely have a single cause.

However, creating a darker sleep environment is one of the simplest ways many families improve their baby’s sleep routine.

By reducing light entering the room, you can help reinforce the signals that support sleep, especially during early mornings and daytime naps.

For us, improving the sleep environment was one of the biggest lessons we learned as new parents, and it ultimately led us to start Porta Fox.

Our goal has always been simple: to help families create beautiful, calm and practical sleep spaces that actually work in everyday life.

Written by

Annette 
Founder, Porta Fox 💜

Kim & Annette are two mums who wanted blackout blinds that worked... without making the nursery look like a cave.