No, a baby sleeping bag (also called a sleep sack) won't make your baby sleep through the night. It's useful for safer sleep.
Baby sleeping bags in brief
A baby sleeping bag won't make your baby sleep through the night: waking for feeds is normal. It helps stop your baby wriggling under covers. Choose the size by your baby's weight, with a good fit at the neck and shoulders. Keep the room at 16 to 20C and put your baby on their back. Put nothing on top of the sleeping bag. Don't use a hat, and weighted sleeping bags aren't recommended for babies under one.
A baby sleeping bag is a wearable blanket that keeps covers off your baby's face
A baby sleeping bag is worn over a baby grow and zipped or fastened in place. It covers your baby's body and legs without loose fabric.
The Lullaby Trust calls sleeping bags a good option for safer sleep because they help stop your baby wriggling down under covers and getting their head covered.1 The NHS says to keep the cot clear of anything that could cover your baby's face and head, so keep loose blankets, duvets, pillows, bumpers and soft toys out of the cot.2
A sleeping bag won't make your baby sleep through the night
Babies don't all start sleeping through the night at the same age. The NHS guidance on helping your baby to sleep says some babies do so quite soon, while others don't for a long time.3 Babies also wake because they need feeding, so waking isn't a reason to assume you've chosen the wrong sleeping bag.
Being too hot or too cold can also disturb your baby's sleep, so match the sleeping bag to the room temperature. A simple, soothing bedtime routine may help your baby settle; there's no need to make it elaborate.
The right sleeping bag fits your baby's weight and suits the room temperature
Most baby sleeping bags are sized by weight rather than age, so check the manufacturer's guidelines before choosing a size. Make sure the bag fits well around your baby's neck and shoulders so they can't wriggle down inside it. Look for the safety standard BS EN 16781:2018.
The bag should fit well at the neck and shoulders so your baby can't wriggle down inside it.
Tog is a measure of warmth. The risk of SIDS is higher in babies who get too hot. The recommended room temperature is 16 to 20C, so use a room thermometer and follow the manufacturer's tog guide. Don't add blankets on top or use two sleeping bags together: air trapped between the bags adds warmth. Take hats off indoors. Weighted sleeping bags are not recommended for babies under one.
How warm is the room your baby sleeps in?
Cooler than 16C. Don't add blankets on top of the sleeping bag. If your baby feels cold, add an extra layer of clothing or choose a higher tog sleeping bag.
16 to 20C, the recommended range. A lightweight, well-fitting baby sleeping bag is comfortable.
Warmer than 20C. Use a lower tog. In hot weather it's fine for your baby to wear a lightweight layer such as a short sleeve bodysuit, or even just a nappy.
Guidance from The Lullaby Trust.
Feel your baby's chest or the back of their neck to check their temperature. Their hands and feet are usually cooler, which is normal. If their chest or neck feels hot or sweaty, remove a layer.
Before each sleep, check:
- Your baby is on their back
- The bag is the right size for their weight
- It fits well around the neck and shoulders
- Nothing is on top: no blanket, duvet or pillow
- No hat, and the bag isn't weighted
- The room is 16 to 20C
- The tog matches the room, following the manufacturer's guide
If your baby has a fever or you are worried about them, you should call your GP or 111.
Stop swaddling with arms inside once your baby shows signs of rolling
Many parents move from a swaddle to a baby sleeping bag. The Lullaby Trust says to stop swaddling with your baby's arms inside once they show signs of rolling, because they could roll onto their tummy and not be able to roll back.4
Stop swaddling with their arms inside once your baby shows signs of rolling, and always put them down on their back.
Never put a swaddled baby to sleep on their front or side. Never swaddle when bed-sharing or if your baby has an infection or fever. Whatever your baby wears, the NHS says to always place them on their back to sleep, in a separate cot or Moses basket in your room for at least the first 6 months.
Questions people ask about baby sleeping bags
What tog sleeping bag does my baby need?
Follow the manufacturer's tog guide for your room temperature. The Lullaby Trust doesn't give a single tog chart because every product and baby differs. Use a lower tog in warmer rooms. Check your baby's chest or the back of their neck to judge how warm they feel.
Can I put a blanket over a sleeping bag?
No, don't add extra blankets on top of your baby's sleeping bag. If your baby feels cold, add an extra layer of clothing or choose a higher tog sleeping bag. Don't use two sleeping bags together: they are warmer than you would expect from adding their tog ratings together.
When can my baby start using a sleeping bag?
Your baby can start using a sleeping bag when they meet the manufacturer's guidance. Most sleeping bags are fitted by weight rather than age. Check the minimum weight and any age guidance for the bag you choose. Make sure it fits well around your baby's neck and shoulders.
