One of the most common questions during that final bedtime check is: is my baby too hot or too cold?

Should they have a vest underneath their sleepsuit? Is a sleep bag enough? What happens when the temperature suddenly drops overnight? And on a warm summer evening, is a sleepsuit too much?

Knowing what your baby should wear to sleep can feel confusing, particularly as the seasons change. But the most important thing to consider isn't actually the weather outside, it's the temperature of the room your baby is sleeping in.

This guide covers what babies can wear at different room temperatures, how to layer baby sleepwear safely, how to tell if your baby is getting too warm and what to consider when choosing comfortable nightwear.

What Is the Ideal Room Temperature for a Baby?

The recommended room temperature for babies is 16–20°C.

A simple room thermometer can be useful because bedrooms can feel warmer or cooler than they actually are, and the temperature when you put your baby to bed may change considerably overnight.

It's particularly important to avoid overheating. Babies who become too hot have an increased risk of Sudden Infant Death Syndrome (SIDS), which is why adding lots of layers "just in case" isn't recommended.

Instead, choose lightweight layers that can be adjusted according to the temperature of your baby's sleep space.

What Should a Baby Wear to Sleep at Different Temperatures?

There's no single outfit that's right for every baby. What they need will depend on the room temperature, the clothing they're wearing and whether you're using a sleep bag or lightweight bedding.

As a general guide:

Below 16°C — A Cooler Room

If your baby's room falls below the recommended 16–20°C range, you may need to add a layer of clothing or choose an appropriately rated warmer sleep bag.

For example, this might mean a bodysuit underneath a sleepsuit, followed by a suitable baby sleep bag.

If you're using a sleep bag, don't simply add blankets over the top. Follow the manufacturer's guidance for the TOG and add an appropriate clothing layer underneath if necessary.

16–20°C — The Recommended Range

This is the recommended temperature range for a baby's sleeping environment.

A sleepsuit worn with a correctly fitting baby sleep bag can be a comfortable option within this range. Exactly what your baby wears underneath will depend on the TOG of their sleep bag and the manufacturer's recommendations.

Lightweight, breathable baby sleepwear can make layering particularly easy because you can adjust what's underneath the sleep bag as temperatures change.

Above 20°C — A Warmer Room

Once the room becomes warmer, reduce the number and weight of layers your baby is wearing.

Depending on how warm the room is, a lightweight sleepsuit or short-sleeved bodysuit may be enough.

In hot weather, babies may need very little clothing. On particularly warm nights, a lightweight short-sleeved vest or even just a nappy can be appropriate.

The important thing is to continue checking your baby's temperature rather than relying entirely on what they're wearing.

What TOG Sleep Bag Does My Baby Need?

TOG is a measure of thermal insulation, essentially, how warm a sleep bag is.

You'll commonly see baby sleep bags available in different TOG ratings for warmer and cooler environments.

Rather than choosing a TOG simply because it's "winter" or "summer", check the temperature of your baby's bedroom and follow the temperature and clothing guidance supplied by the manufacturer of your particular sleep bag.

You'll then need to consider what your baby is wearing underneath it.

A thicker sleep bag plus several warm clothing layers could leave a baby too hot, while a lighter sleep bag may require a different combination.

Think of the sleep bag and clothing together, rather than as separate decisions.

Should My Baby Wear a Vest Under Their Sleepsuit?

Sometimes, but not always.

Whether your baby needs a bodysuit or vest underneath their sleepsuit depends on the temperature of the room and what other bedding or sleep bag they're using.

On a cooler night, a lightweight bodysuit underneath a sleepsuit can provide an additional layer.

On a warmer night, that extra layer may not be necessary.

This is why having a mixture of short-sleeved bodysuits, long-sleeved baby sleepwear and sleepsuits can be useful throughout the year. Instead of completely changing their sleepwear every season, you can adjust the layers as the temperature changes.

How Can I Tell If My Baby Is Too Hot?

Don't judge your baby's temperature by their hands or feet.

It's normal for a baby's hands and feet to feel cooler than the rest of their body.

Instead, feel your baby's chest or the back of their neck.

If their skin feels hot or they're sweating, remove one or more layers of clothing or bedding.

A room thermometer can also remove some of the guesswork, particularly during seasonal changes when bedrooms may become considerably cooler overnight.

What Should a Baby Wear to Sleep in Winter?

When colder weather arrives, it's tempting to bundle babies up, but more isn't necessarily better.

Aim to keep their room within the recommended 16–20°C range where possible and adjust their sleepwear accordingly.

A breathable sleepsuit combined with an appropriately rated sleep bag may be all that's needed. If your baby feels cold, consider adding a clothing layer underneath or choosing a higher-TOG sleep bag rather than piling additional blankets on top.

And remember that a cold night outside doesn't necessarily mean a cold bedroom. Central heating and insulation can make indoor temperatures surprisingly warm.

Always dress your baby for their room, not the season.

What Should a Baby Wear to Sleep in Summer?

During warmer weather, the opposite applies.

Keep sleepwear lightweight and reduce layers as the room gets warmer.

A breathable sleepsuit may work on a mild summer evening, while a short-sleeved bodysuit can be useful when the bedroom is warmer.

During very hot weather, it's fine for babies to sleep in minimal clothing, such as a lightweight vest or even just their nappy.

You can also help keep the room comfortable by closing curtains during the hottest part of the day, safely allowing airflow and using a fan to cool the room — but don't point the fan directly at your baby.

Why Fabric Matters for Baby Sleepwear

Temperature isn't the only thing to consider when choosing what your baby sleeps in.

Babies spend many hours in their nightwear, so choosing soft, comfortable fabrics that sit gently against their skin can make a difference.

Bamboo baby sleepwear has become a popular option because it feels beautifully soft and lightweight while offering plenty of stretch for wriggling, rolling and growing babies.

Stretch is particularly useful during the first year when babies seem to outgrow their clothes almost overnight.

Breathable, lightweight layers are also easier to combine with a baby sleep bag without adding unnecessary bulk.

Baby Sleepwear for Every Season

Having a few versatile sleepwear options makes it easier to adjust what your baby wears as their room temperature changes. From lightweight organic cotton to soft bamboo layers, these are some of our favourite pieces for comfortable bedtimes throughout the year.

Can Babies Wear Socks to Bed?

If your baby is wearing a footed sleepsuit, they generally won't need an additional pair of socks underneath.

If they're wearing footless pyjamas or a bodysuit, whether they need socks will depend on the room temperature and the rest of their clothing.

Again, don't use cold feet alone as a sign that your baby needs another layer, check their chest or the back of their neck instead.

Should Babies Wear Hats to Sleep?

No. Babies shouldn't wear hats indoors while sleeping.

Babies lose excess heat through their heads, so covering their head while they're sleeping indoors can increase the risk of overheating.

Remove outdoor hats and extra layers when you come inside, even if your baby has fallen asleep.

What If My Baby Has a Fever?

If your baby is unwell or has a fever, don't automatically add extra layers because they feel poorly.

Babies with a fever generally don't need additional clothing. Keep checking their temperature and seek appropriate medical advice if you're concerned about an unwell baby.

A Simple Bedtime Temperature Check

Before putting your baby down for the night:

• Check the bedroom temperature rather than relying on how it feels.
• Consider every layer they're wearing, including their sleep bag.
• Make sure their sleep bag fits correctly around their shoulders.
• Keep their head uncovered indoors.
• Don't place their sleep space beside a radiator, heater, fire or in direct sunlight.
• Check their chest or the back of their neck if you're unsure whether they're comfortable.
• If they're hot or sweaty, remove a layer.

The aim isn't to make your baby feel particularly warm and cosy, it's to keep them at a comfortable temperature throughout their sleep.

A Gentle Reminder

It's completely normal to wonder whether your baby is warm enough, particularly during those first months or when the seasons begin to change.

But babies don't need to be bundled up to sleep comfortably.

Focus on the temperature of their room, choose lightweight and breathable baby sleepwear, follow the guidance supplied with your baby's sleep bag and check your baby's chest or the back of their neck if you're unsure.

As temperatures change throughout the year, having a few versatile layers, from lightweight bamboo bodysuits to comfortable sleepsuits and pyjamas, makes it easier to adapt without overcomplicating bedtime.

The goal isn't to find one perfect bedtime outfit. It's simply to keep your baby comfortable, safely dressed and ready for sleep.