Dress your baby for the temperature of the room they sleep in, keep their head uncovered, and use a well-fitting sleeping bag or lightweight, firmly tucked bedding rather than loose blankets. The Lullaby Trust and the NHS suggest a sleeping room of about 16–20°C, and a sleepsuit plus sleeping bag is a typical outfit in that range. Red Nose in Australia doesn't set a room temperature and simply says to dress your baby as you would dress yourself. Whatever you choose, check your baby's chest, back of the neck or tummy, and take a layer off if they feel hot or sweaty.
Why does it matter what my baby wears to sleep?
Overheating is a known SIDS risk. The NICHD Safe to Sleep FAQ says overheating from too much clothing or bedding and a high room temperature are associated with a higher SIDS risk, and the AAP's safe sleep guidance says the same. The Lullaby Trust's cold weather advice puts it simply: babies are safer a little cooler than too hot.
So when you're unsure, lean towards fewer layers and check your baby, rather than adding another blanket "just in case". The rest of the safe sleep basics still apply: on the back, in their own cot or bassinet, with a firm, flat mattress and nothing soft or loose in the sleep space. See safe sleep and sleep environment.
What room temperature is best for a sleeping baby?
This is the clearest regional difference in dressing advice.
| Source | Room temperature advice |
|---|---|
| Lullaby Trust (UK) | 16–20°C, checked with a room thermometer |
| NHS (UK) | About 16–20°C |
| Red Nose (Australia) | No specific figure; dress for the room |
| AAP (US) | No figure; avoid overheating |
The Lullaby Trust's dressing card recommends 16–20°C and suggests a room thermometer because temperature is hard to guess, while stressing that this is a guide only. The NHS SIDS page gives the same range.
Red Nose in Australia takes a different view. It says there is no evidence that a particular room temperature prevents sudden infant death, that a room temperature monitor isn't necessary, and that heating or cooling doesn't need to run all night. Both approaches aim at the same thing: a baby who is comfortably warm, not hot.
How many layers should a baby wear to bed?
There are two common rules of thumb, and they come from different countries:
- Red Nose (Australia): dress your baby as you would dress yourself for the temperature of the room.
- AAP (US): dress your baby in only one layer more than you're wearing.
A sleeping bag counts as a layer. Australia's Red Nose suggests a sleeveless, legless bodysuit or just a nappy and vest in warm weather, and a full suit in cooler weather. Natural fibres such as cotton are a good choice underneath a sleeping bag, according to Australia's Red Nose's sleeping bag guide.
Example outfits by room temperature
These examples follow the Lullaby Trust's card. Adjust them to your baby and check how they feel.
| Room | Example outfit |
|---|---|
| Cooler than 16°C | Extra clothing layer or higher-tog bag; no extra blankets on a bag |
| 16–20°C | Sleepsuit and sleeping bag, or sleepsuit and a tucked lightweight blanket |
| Warmer than 20°C | Short-sleeved bodysuit, or just a nappy |
| Much warmer, or heatwave | Short-sleeved vest or just a nappy |
For a young baby who is still wrapped, see swaddling: Australia's Red Nose suggests only a nappy and vest under the wrap in warm weather and a lightweight suit in cooler weather.
Are sleeping bags safer than blankets, and what tog should I use?
Sleeping bags keep a baby warm without loose bedding that could cover their face. Australia's Red Nose says a safe sleeping bag:
- fits your baby's size, with fitted neck and armholes (or sleeves) so they can't slip down inside
- has no hood
- leaves the arms free once your baby shows signs of rolling
- is not weighted and doesn't restrict arm movement
- never has extra blankets added on top
The Lullaby Trust adds that most bags are sized by weight rather than age, so check the maker's guide, and if your baby seems cold, add a clothing layer or choose a higher-tog bag rather than putting a blanket on top.
On tog: Red Nose says to choose a lower tog for warmer weather and a higher tog for cooler nights, matched to the room, and notes there's no specific Australian standard for tog ratings. The Lullaby Trust says it can't give tog-by-temperature advice. So use the chart from your sleeping bag's manufacturer, and check your baby rather than relying on the number.
If you use blankets instead
Blankets are an option in Australian and UK guidance but not in US guidance. The AAP advises keeping loose bedding out of the cot and using layers of clothing or a wearable blanket if your baby seems cold. If you do use blankets, Australia's Red Nose and the Lullaby Trust say:
- Put your baby on their back with their feet at the bottom of the cot (feet to foot), so they can't wriggle down under the covers.
- Use lightweight cotton or muslin sheets and blankets, not thick, fleecy or padded ones, duvets or duvets.
- Tuck them in firmly, no higher than your baby's shoulders.
- Count carefully: the Lullaby Trust notes that one blanket folded double counts as two.
Should babies wear hats or beanies to sleep?
No, not indoors. The AAP says not to put a hat on your baby indoors once you're home from hospital. The NHS says to remove hats and extra clothing as soon as you come indoors, even if it wakes your baby. The Lullaby Trust says not to let babies sleep in hats, hoods or outdoor clothing, and Australia's Red Nose says to remove head coverings for sleep so the head and face stay uncovered.
The same goes for outdoor gear. Take off coats, snowsuits and hoods once your baby is inside, including when they've fallen asleep in a pram or car seat on the way home.
How do I check if my baby is too hot or too cold?
Hands and feet are usually cooler than the rest of the body, and that's normal. Instead:
- Lullaby Trust (UK): feel the chest or the back of the neck.
- Red Nose (Australia): feel the tummy, which should feel warm.
| What you feel or see | What to do |
|---|---|
| Warm, dry chest, neck or tummy | Nothing; your baby is comfortable |
| Cool tummy or chest | Add a light layer of clothing |
| Hot, sweaty or clammy skin | Remove a layer or some bedding |
| Damp hair, flushed cheeks, heat rash | Remove layers and cool the room |
The AAP's swaddling advice lists sweating, damp hair, flushed cheeks and heat rash as signs a baby is too hot. If your baby still seems hot after you've removed layers, check their temperature, because a fever is a different problem from overdressing (see fever in babies).
How should I dress my baby for sleep in summer and winter?
Summer
- A short-sleeved bodysuit, vest and nappy, or just a nappy in very hot weather.
- A low-tog sleeping bag or a single lightweight, firmly tucked sheet, or nothing extra if the room is very warm.
- A fan can move air around the room, but Australia's Red Nose says not to point it directly at your baby.
- See hot weather for prams, cars and fluids.
Winter
- A long-sleeved sleepsuit, with an extra light layer underneath if the room is cool.
- A higher-tog sleeping bag, chosen using the maker's guide, with no blankets on top.
- Keep the cot away from radiators and heaters, and point portable heaters away from your baby, as the Lullaby Trust advises.
- The Lullaby Trust says never to use a hot water bottle in a baby's sleep space.
When to get help
These signs are on the NHS list of when to get urgent help, which also includes a temperature below 36°C. If your baby still feels hot after you've removed layers, seems unwell or you're not sure, call NHS 111 or your GP for advice the same day.
Mention at the next check: questions about tog, room temperature or what suits your home, especially if your baby was premature or has a health condition. Your GP or health visitor can help you tailor the basics.
