Is my baby too hot or too cold for sleep?

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Baby sleeping in Joey Swag baby sleeping bag

The one question we get asked time and time again – “is my baby too hot or too cold for sleep?”.

It’s a good time to turn your attention to what your little one is wearing to bed to ensure a blissful and safe night’s sleep. Like us, our little people need to be comfortably warm for a sound night’s sleep. Overheating has long been linked to Sudden Infant Death Syndrome (SIDS). Being too cold can disturb a baby’s sleep and inhibit weight gain. Is your baby too hot or too cold for sleep?

All babies are different, just like adults. My husband sleeps in boxer shorts all year round whereas in cooler weather I’m in long pyjamas and a singlet with extra layers of bedding. I’ve found that my kids are also different – my son takes after me more and feels the cold, whereas my daughter runs hot and takes after her Daddy.

Is my baby too cold?

We lose body temperature through exposed body surfaces. This is called “radiated heat” by the Mayo Clinic. Basically, exposing your skin typically causes you to lose heat. Babies in particular CANNOT regulate their body temperature as well as an adult because:

1. babies have a high body-surface to weight ratio.

A baby’s body surface is about three times greater than an adult’s, relative to their weight, so they can lose heat rapidly – as much as four times quicker than adults.

2. babies don’t have the physical skill or mental awareness to self-regulate like adults do.

Your first instinct may be to check your baby’s hands and feet to see whether they feel cold but this is not a good way to tell if your baby is too cold. This is because a baby’s hands and feet are often exposed and as such normally will feel cold! If your baby’s hands and feet are cold, this does not necessarily mean that your baby is too cold!

The best way to check your baby’s temperature is to feel their chest. Baby’s chest should feel warm. A lot of development is happening in the core of newborns so blood is naturally diverted to this area.

When babies are cold, they use energy and oxygen to generate warmth. By keeping your baby at his or her optimal temperature, they can conserve energy and build up reserves. When your baby’s temperature is regulated and maintained, a baby will be more relaxed, they sleep longer and gain weight. This is especially important when babies are sick, premature or of low birth weight.

Babies that behave like babies are more than likely not too cold. You should stay in tune with your baby’s behaviour. Is your baby eating, sleeping, crying, and being a normal baby? If so, your baby is more than likely fine. However, if you do have any concerns then seek advice from a healthcare professional.

Is my baby too hot?

When dressing your baby for sleep, it’s easy to get carried away in some instances and cause your baby to overheat. This can be a serious threat to your baby’s health. Overheating a baby has been linked to an increased risk of SIDS . The signs of overheating in a newborn are easy to detect.

Always dress your baby in natural fabrics that breathe as this will help reduce the chance of overheating. These include cotton and wool baby sleeping bags rather than polar fleece sleepwear. Also ensure that the layers underneath the baby sleeping bag are natural fabrics as well, such as cotton onesies or pyjamas not polyester.

The best way to check if baby is too hot is to touch your baby’s chest or head and neck to check for dampness, if your child is damp this is a sign that they’re sweating and they’re overheating. As advised above, if your baby’s chest is too warm this is also a sign that they’re too hot. You should also listen to your child’s breathing, or watch the rise and fall of her chest. Rapid breathing is another sign of overheating. There is some suggestion that overheating could play a role in SIDS.  Put simply, SIDS is the inability for a baby to wake when something else is going wrong physiologically. Studies have found that higher room temperatures make it more difficult to rouse the baby therefore increasing the chance that your baby won’t wake if something is going wrong.

SIDS Evidence

Gwen Dewar provides scientific discussion in her article What is SIDS? An overview for the science-minded parent © 2009 -2014.** It seems that the brain may have more trouble awakening when overly warm. A hotter room may mean that baby is less likely to arouse from sleep than lower temperature rooms.

The reason why you want to keep the room temperature lower is so your baby is able to wake and cry if something is indeed happening during sleep.

If your baby has any signs of overheating, remove some bedding or clothing. This may be necessary if your baby is unwell, in which case you need to seek medical attention from a health care professional.

How can I make sure my baby is kept at the right temperature for sleep?

Babies control their temperature predominantly through their head and face*. Sleeping your baby on their back with the head and face uncovered is the best way to protect your baby from overheating. Once your baby is rolling, using a baby sleeping bag ensures they don’t become entangled in blankets and sheets, therefore minimising the risks of overheating and suffocation. A sleeveless baby sleeping bag allows for airflow through the arm holes.

It is not necessary to monitor the room temperature or to leave the heating on all night as long as the baby is dressed appropriately for the room temperature. Somewhere between 16-20⁰C is an optimal temperature.  You should dress your baby for the coolest part of the night.  If you think that baby will be too warmly dressed initially then you can open the bedroom window or door to allow airflow.

As advised above, if your baby has any signs of overheating, remove some bedding or clothing. This may be necessary if your baby is unwell, in which case you should seek medical attention from a health care professional.

What not to do

If you are returning home from an outing and putting baby straight to bed then remove baby’s hat or bonnet. Even if it wakes baby, it’s safer than overheating. Never use electric blankets, wheat bags or hot water bottles for babies. Keep the baby’s cot well away from heaters and radiators. Do not use cot bumpers as these prevent air flow.

Baby just right for sleep - not too hot or too cold

Swaddling baby

Newborns and babies not yet rolling independently can be swaddled for safety and comfort until their startle reflex settles down but you definitely need to stop swaddling before baby  begins to roll from their back to their tummy.

Our Joey Pouch Swaddling Wrap is designed specifically for newborn babies. The Joey Pod Transitional Swaddle Bag can be used as a swaddle, one arm in one arm out or like a baby sleeping bag. Both the Joey Pouch and the Joey Pod are made from a beautiful light-weight 100% knitted cotton waffle fabric. This provides natural give and can be used all year round. Every Joey Pouch and Joey Pod comes with a door hanging temperature guide. Just refer to the Temperature Guide for how to dress your baby depending on the temperature of baby’s room:

Joey Pouch Temperature Guide



Joey Pod Transitional Swaddle Temperature Guide

For cold nights, clothing underneath the swaddle can include 100% cotton/natural fibre singlets, vests or onesies.   Bear in mind that a swaddle is like a pouch or cocoon where baby’s arms and whole body are wrapped generating their own heat.  As such a lightweight swaddle is recommended because you don’t want to overheat your baby. Our Joey Pouch and Joey Pod and are made from light-weight 100% knitted cotton waffle and TOG/warmth rated at 0.5TOG.

If you feel that your baby may be cold when swaddled then simply add a layer of clothing or a 100% cotton blanket over the top. It’s fine to use a blanket when baby is still swaddled as they’re not rolling around the cot.  If your baby shows signs of rolling then it’s time to stop swaddling and transition to a baby sleeping bag.  You can find out how to stop swaddling in our 3 step transition out of swaddling plan.

Baby not too hot or too cold for sleep

Baby Sleeping Bag

A baby sleeping bag is a wearable blanket that can be used for babies from 4kg. Once your baby has started rolling over independently or moving around the cot then a baby sleeping bag is essential. Baby sleeping bags are a safe and convenient way to ensure your baby is dressed appropriately for bedtime. Most are TOG/warmth rated, like a duvet, doona or quilt. TOG is a European measure of thermal resistance relative to surface area – the higher the TOG rating the warmer the garment.

When you choose a suitable TOG rated baby sleeping bag for your baby, you also need to consider the clothes your baby is wearing, the temperature of their bedroom and your baby’s health. Baby sleeping bags padded with wool offer greater insulation without adding weight and bulkiness. Our 1.5TOG & 2.5TOG Platinum Joey Swag baby sleeping bag range is made from 500 thread count organic cotton and is padded with Australian wool.

In a review of published and unpublished literature on the role of wool in human health and well-being by Raechel Laing and Paul Swan it was found that:

“Wool fabrics are regarded as providing superior thermal properties under both damp and wet conditions.  The small amount of heat released with absorption of water, and wool fibres reported as having low thermal conductivity than cotton, polypropylene or acrylic,”.

In layman’s terms this means that wool is a great natural insulator. It keeps you warm in cooler weather and cool in warmer weather.  This is the reason why wool batting is used to insulate homes and properties!

So how do you dress baby to make sure they are not too hot or too cold for sleep? The guide below, for our Platinum baby sleeping bag ranges, will help you dress your baby appropriately whatever the season.

What To Wear So Baby Is Never Too Hot Or Too Cold

What to Wear so Baby Is Never Too Hot or Too Cold

All Bubbaroo Joey Swag Baby Sleeping Bags have a front zip, ideal if your child moves around. All Joey Swags feature YKK brand two-way zip and a slit at the back closed with beautiful soft Velcro. This allows all of our Joey Swags to be used with a 3 or 5 point harness of a car seat or pram/buggy.

Bubbaroo can help you and your baby to sleep better no matter what the temperature!

Sweet dreams!


*Ref: Red Nose (formerly SIDS and Kids) Safe Sleeping. This program is based on scientific evidence and was developed by Australian SIDS researchers, paediatricians, pathologists, and child health experts with input from overseas experts in the field.



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