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Should I Choose Natural Fibre or Polyester Fill for my Baby’s Sleeping Bag?

Should I Choose Natural Fibre or Polyester Fill for my Baby’s Sleeping Bag?

At The Sleep Store we stock a large range of baby sleeping bags and suits, to ensure we have something that caters for all our customers’ needs and budgets. Choosing whether to buy a bag with a natural fibre filling such as cotton or merino or a polyester filling will come down to personal choice and both options have pro’s and con’s. It simply comes down to what works for you, your baby, and your budget!  

Merino Fill Sleeping Bags

For breathability and temperature regulating properties, you can’t beat merino. The natural wool fibre draws moisture away from the skin so your baby won’t get so clammy when hot. Merino wool also creates an air pocket to help the wearer’s temperature remain consistent - not too hot and not too cold. This also means they can be used in a wider range of temperatures which is great for room which are warm at the start of the night and then drop quickly as the night cools. Most modern merino is easy to care for, although it still needs to be air dried and washed on a delicate wool wash cycle with special wool wash detergent and under 800rpm spin.


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Cotton Fill Sleeping Bags

Cotton is another natural fibre we love, again for it’s breathability and smooth feel on the skin, which is perfect for babies with eczema. Cotton is easier to care for as you can wash it on a normal cycle and put it in the dryer (take care to read care instructions for individual garments). There are options for organic cotton such as Woolbabe (the duvet weight is lined with 100% organic cotton) or Ergopouch..


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Polyester Fill Sleeping Bags

Whilst not a natural fibre, polyester is a good option when used as a filling as it can keep the cost of a sleeping bag down and is easy to wash and dry. This makes these bags a budget-friendly option for day care or as a second bag to keep at a relative’s house. Polyester fill also maintains a consistent tog rating which is important to some people. Polyester fill bags aren’t necessarily bad quality or unsafe - we would not stock any sleeping bags which are unsafe for babies to use, regardless of their fill.


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Here’s some points to consider when choosing what filling you want for your baby’s sleeping bag:

1. Price range: Not everyone can invest in a Woolbabe or 100% Merino sleeping bag or you may want a cheaper option as a spare. At The Sleep Store we have Winter Sleeping bag options that range from around $50 up to around $200. Merino bags tend to be more expensive and cotton or polyester options are cheaper.

2. Where you will use the bag: People may choose to purchase a natural fibre sleeping bag with a higher price point for regular use at home, but might go with a lower price point bag for their little one to use at daycare or as a back-up for spills and the inevitable nappy explosion! Allergies: Sleeping bags with polyester filling are allergy friendly and can be washed at a higher temperature which kills dust mites. This is a massive benefit for little ones with allergies.

3. Ease of Care: If you want something that you can throw in a normal wash and use in a hot dryer, 100% cotton or polyester fill bags are best. Any bags with merino need to be washed on a wool wash with a specific liquid wool wash detergent and air dried, which can take a lot longer.

4. Size range of the bag: Some more affordable sleeping sacks are sized to fit over a narrower age range than some of the more expensive range. Consider that you’ll be using a sleeping bag for at least a couple of years and weigh up whether you’re happy to keep buying the next size up every 6-9 months or would like to pay more up front and get a sleeping bag which can be used for 18 months to 2 years and may cost less in the long run. Make sure you double check the sizes as well as the age range of the sleeping bags as some brands size differently to others. For example, Woolbabe is quite generous in it’s sizing with many customers getting the full age-range of use and sometimes longer out of their child’s sleeping bag.


We’re passionate about safe sleep and high quality products and would not stock any sleeping bags that are unsafe for your baby to use, regardless of the filling used, providing you’re using them to the guidelines.

Regardless of what a sleeping bag is filled with or made from, or what brand you choose, we always suggest checking your little ones body temperature to make sure they are not overheating, too hot or sweaty. Checking behind your little ones neck between shoulder blades, will give you a good idea of their temperature.