Safer Sleeping Guide for Baby Sleeping Bags

One of the most important factors to consider to ensure safer sleep for your baby is temperature, particularly to reduce the risk of overheating. This is consistent across the major advice groups including the UK’s biggest SIDS research and advisory body, The Lullaby Trust.

The Lullaby Trust and other such organisations recommend the use of baby sleeping bags as one of the safest ways for your babies to sleep. However it’s really important to consider the fabrics in these sleeping bags, as some of them may actually be working against your babies’ natural ability to regulate their temperature. There are also other safety factors to consider when choosing a sleeping bag, which we’ve summarised for you below:


Sleeping bags made of 100% natural fabrics will be the safest choice for reducing the risk of overheating. Natural fabrics are much more breathable and allow for greater temperature control than their synthetic counterparts. 

Unfortunately, the most popular filling for baby sleeping bags is polyester wadding. Polyester actually impairs the body’s natural ability to regulate temperature and can very quickly cause overheating if not used correctly. All sleeping bags sold with polyester inside will come with a warning about the temperature limits for that specific tog rating (which will typically be just a 3-4 degree limit). This means a lot of guess work is involved before putting your baby to bed: you’ll need to estimate what the likely temperature of the room will be that night, which tog bag to choose and how many under layers to dress your baby in too. 

There are several natural alternatives on the market to these polyester-fill sleeping bags. Currently available on the market are bags that have wool or bamboo inside the outer layer of cotton. 

Wool-fill bags: These are a much safer option in regards to temperature regulation than polyester, but they may not be so practical for washing or if your baby has sensitive skin or eczema. While a huge step up in terms of safety and babies’ comfort from their synthetic counterparts, you’ll still need to buy one for summer and one for winter, as the temperature ranges on these bags cannot usually cover all the seasons. 

Bamboo-fill bags: Bamboo fabric is thought to be the leading fabric for thermoregulation. It is proven to work with our bodies to maintain a more constant temperature than other fabrics. For this reason bamboo wadding sleeping bags offer year-round comfort and reduced risk of overheating. The natural micro holes in the fabric draw up to 3x more water away from the body, creating a cooling ventilation system on hot nights, and warm air pockets on colder evenings.

View our range of thermoregulating baby sleeping bags >


This is such an important safety factor, and one which is heavily regulated by the British safety standards BS8510:2009. The neck size of your sleeping bag is crucial to ensure a baby’s head cannot slip down inside the bag. This would cause a huge risk of overheating 

if their head gets covered with the bag. There are some important factors to consider in this regard when choosing your bag. 

Firstly, it is not compulsory for sleeping bags sold in the UK to be compliant with these regulations, so make sure the bags you are buying do comply with BS8510:2009. 

Secondly, not all bags which claim they comply with these standards actually do. This is particularly true on neck sizes and easy to determine for yourself. Neck sizes for babies aged 0-6 months have a very specific limit, as do the neck sizes for babies over 6 months, and there is no overlap in these limits. Therefore, if a sleeping bag is aimed at an age range 0-2 years (or 0-1 year), and does not have an adjustable neck size, then the sleeping bag is not compliant with this part of the regulation. The neck size of the bag must be able to be adjusted for these age ranges in order to safely fit smaller and larger babies alike. 

Thirdly, even though there are strict size limits set by the regulators for these age groups, the regulators themselves will admit that there is some ambiguity around the ‘average’ size of babies in these age ranges. Therefore it’s really important for parents to ensure that their baby’s head is not able to pass through the neck fitting when the bag is properly done up. If your baby’s head is smaller than average, you may need to wait a few more weeks before putting your baby to sleep in a bag labeled to fit a newborn. If there is any risk of the baby being able to slip inside the bag then do not use it until your baby is bigger.

View our range of clever sizing baby sleeping bags >


This point is particularly important if you choose to buy a polyester-fill sleeping bag. Always check the instructions that come with your sleeping bag to ensure the right bag is being used for all the possible temperature changes in your baby’s room. Again, we would recommend that choosing a 100% natural fabric bag is a much safer option as the temperature range will be much larger, and therefore there is less room for error when choosing your baby’s bedding each evening.


This is an important part of the safety regulations. All bags which comply with BS8510:2009 will have passed a flammability test. However, this does not mean that the bags are not flammable, and it’s important to keep babies in sleeping bags away from naked flames at all time. Polyester, for example, is very flammable and when alight will melt, which can cause serious harm.


Whether you’re an instruction reader or not it’s actually really important when it comes to baby sleeping bags. All sleeping bags must legally be sold with instructions for use, and it’s crucial you read these as they will be specific to the sleeping bag you have bought.


Take time to choose your baby’s bedding to ensure what you are buying is right for you and your family. Don’t be tricked by clever marketing – be careful to read labels as companies often make claims that bags are 100% natural fabrics when actually in the small print you will see that they have polyester inside. And double check fittings and neck sizing to ensure that companies are complying with the claimed regulations and also to make sure that your babies are the right size for the bags when they are tried on. 

Regardless of what bag you end up choosing, check on your babies regularly to ensure they are a comfortable temperature in their sleep.