How to Dress a Baby for Sleep (by Room Temperature)

It's bedtime, there's a sleeping bag in one hand and a onesie in the other, and the nursery already feels cooler than it did at dinner. Working out what your baby should wear can feel like guesswork, especially at the 2am feed when you start second-guessing every layer.

The reassuring part is that Australia's safe sleep advice boils down to a simple rule, a quick tummy check and a few sensible layers, and plenty of Mummas find the onesies and bodysuits already in the drawer cover most nights of the year.

How to Dress Baby for Sleep

Red Nose's rule of thumb is to dress your baby the way you'd dress yourself to feel comfortable in that same room. Raising Children suggests fitted layers rather than one thick outfit, so you can add or take one away as the temperature changes.

Overheating is the main thing to watch for. Red Nose explains that research links a baby becoming too hot with a higher risk of sudden unexpected death in infancy (SUDI), which includes SIDS. Babies mainly control their temperature through the head and face, so both need to stay uncovered.

Red Nose's reassurance for parents is that three things protect against overheating: sleeping on the back, keeping the head and face uncovered, and wearing clothing that suits the room.

Hats, beanies, bonnets and topknots all come off before sleep, including the matching one from an outfit set. They hold in heat, and Raising Children warns that headwear can slip down and cover your baby's face. Take them off before every nap as well as at bedtime.

When you count layers, include the sleeping bag or wrap as one of them. Everything underneath adds to its warmth, so a warmer bag usually means a lighter outfit.

Room Temperature Guide: What Baby Wears to Sleep

Red Nose doesn't recommend a set room temperature, because there's no evidence that any one number prevents sudden infant death. It also considers a room thermometer unnecessary, along with leaving the heating or cooling on all night, and recommends adjusting your baby's clothes to suit the room instead.

Use the table below as a starting point for choosing layers. You don't need a thermometer to use it: how the nursery feels to you in light clothing is enough to pick a row, and a tummy check tells you whether you've got it right.

TOG (Thermal Overall Grade) describes how warm a sleeping bag is, and Australian bags are rated between 0.2 TOG for hot weather and 3.5 TOG for cold rooms. Charts differ between brands, so the chart for the bag you own always comes first.

1) Hot Nights (24°C and Above)

On a muggy January night, a nappy and singlet, or a bodysuit with no sleeves or legs, is often enough under a 0.2 TOG bag. A single lightweight bodysuit from our summer bodysuits range can be that one base layer.

A fan helps on humid nights if it moves air around the room and isn't pointed at your baby. Red Nose cites research suggesting a fan that turns side to side may help make sleep safer in some circumstances.

Hot nights can also mean extra feeds. Pregnancy, Birth and Baby says babies under six months still need only breast milk or formula in the heat, and suggests offering feeds more often. For more on dressing through the warmer months, see our guide on how to dress a newborn in summer.

2) Mild Nights (18 to 23°C)

Most Australian spring and autumn nights land somewhere in this range. At the warmer end, a short-sleeve bodysuit under a 1.0 TOG bag usually does it. As the room cools towards 18°C, move to a long-sleeve bodysuit or a footed onesie.

At 20°C, a long-sleeve bodysuit or onesie under a 1.0 TOG bag is a good place to start. Some charts pair a 2.5 TOG bag with a lighter outfit at the same temperature, so check yours.

A footed onesie keeps the feet covered, so you can skip socks. Our newborn knitted bodysuits in soft cotton knit sit comfortably under a bag at the cooler end of this range.

3) Cool and Cold Nights (Below 18°C)

Winter nights, and bedrooms without heating, call for a full-length suit or a long-sleeve bodysuit with leggings under a 2.5 TOG bag. Once the room drops below 16°C, many bag charts move up to 3.5 TOG.

On cold nights, a cotton knitted romper such as our Knitted Romper in oat can be the base layer under a 2.5 or 3.5 TOG bag.

Two thinner fitted layers are easier to manage than one thick one. If your baby feels warm at a resettle, you can take one off without changing everything.

However cold the room gets, the warmth should come from clothing and the bag. Red Nose says to keep lambswool and cot overlays out of the cot altogether, as both raise the risk of overheating.

Wrap, Sleeping Bag or Blanket: What Changes

1) Under a Wrap

A wrap (or swaddle) for sleep should be light cotton or muslin. Because the wrap counts as a layer, dress your baby a little lighter underneath: a nappy and singlet when it's warm, or a lightweight jumpsuit when it's cool, is usually enough.

Keep the wrap below the shoulders and firm without being tight, so your baby's hips and chest have room to move. Red Nose says to stop wrapping as soon as your baby shows signs of rolling, which is typically around 3 months.

Never wrap a baby inside a sleeping bag, and avoid wrapping when you're co-sleeping, since Raising Children notes your baby can get too hot. For the full technique, our step-by-step guide covers how to swaddle a baby safely.

2) Under a Sleeping Bag

A safe sleeping bag has:

• A fitted neck

• Armholes or sleeves

• No hood

• A size that suits your baby, so it can't ride up over the face and head

• No added weight

A TOG rating tells you about warmth only. Red Nose notes there's no specific Australian safety standard for TOG ratings, so always read it alongside the room temperature and the bag's own instructions.

Once your baby shows signs of rolling, Red Nose says their arms need to be free during sleep, so switch to an arms-free bag. There’s no set age for stopping, but Red Nose recommends taking the bag away once your child moves from a cot into a bed, because a bag can trip them when they get up.

3) With a Blanket Instead

If you'd rather use a blanket, choose thin, lightweight cotton. Red Nose's guidance is to put your baby down with their feet at the bottom of the cot, then tuck the blanket in firmly on three sides so it comes up no higher than the chest.

Dress your baby warmly enough underneath that they'll still be comfortable if they wriggle out from under it. If you're co-sleeping, keep your baby's space clear of all bedding.

How to Tell if Baby Is Too Hot or Too Cold

Feel your baby's tummy, chest or the back of the neck. Red Nose says cool hands and feet are normal, even when your baby's tummy feels comfortably warm.

Signs your baby may be too hot:

• A hot or clammy tummy

• Flushed, clammy skin

• Sweating

• Breathing faster than usual

If you notice any of these, take off a layer or swap to a lower TOG bag.

A cool tummy may mean your baby needs another layer, and a baby who's cold will usually wake. Add one layer, then check again a little later.

Check after you've settled your baby and again at each overnight feed. A hand on the tummy only takes a few seconds.

Feeling Warm or Running a Fever

A temperature of 38°C or higher is a fever. Healthdirect advises that a baby under 3 months with a fever needs to go to the nearest emergency department straight away. For an older baby, see a doctor if you're worried.

Either way, resist the urge to bundle them up. Red Nose advises fewer bedclothes for a baby with a temperature.

Heaters, Air-Con and the Overnight Temperature Drop

Plenty of Australian bedrooms cool off between bedtime and the early hours, especially in homes without central heating. A drop of a few degrees overnight is normal, and Red Nose's main message is to avoid overdressing.

Dress your baby for the room at bedtime, then feel their tummy at feeds. If it's cool, add a layer under the sleeping bag. A bag also suits babies who kick off blankets, because it stays put all night.

With a heater or air-con running, dress your baby for the temperature the room reaches with it on, whatever the season outside. An air-conditioned bedroom in January may need a 1.0 TOG bag. Keep the cot away from heaters and other electrical appliances.

Hot water bottles, wheat bags and electric blankets should never be used for babies. Keep the warmth in their clothes and sleeping bag instead.

Naps in the Pram or Car

Take off outdoor layers and hats as soon as your baby is indoors or in a warm car, even if it wakes them. Never drape a muslin or wrap over the pram, because even light fabric reduces airflow and traps heat inside.

Fabrics and Fit for Sleepwear

Red Nose recommends lightweight fabrics such as cotton and muslin for wraps, sheets and blankets. For clothing, the principle is the same: a warmer fabric means fewer covers. Soft cotton, cotton waffle and cotton knit all make comfortable base layers under a bag or wrap.

Sleepwear should sit close to the body with room to move, and no loose fabric near the face. Health authorities advise against cords, drawstrings and ribbons on baby clothes because of the strangulation risk, so keep pieces with ties or bows for daytime photos.

Press studs and zips speed up overnight nappy changes, and spares help when a 2am change turns into a full outfit swap. Our Textured Knit Bodysuit Trio gives you three 100% cotton knit bodysuits in ivory, coco and oat.

Australia's mandatory nightwear standard labels children's sleepwear by fire risk, and close-fitting garments are less likely to catch alight. Pregnancy, Birth and Baby calls close-fitting nightwear with a low fire danger label the safest choice.

If a piece looks tight across the shoulders, or your baby's toes press against the end of a footed suit, it's time to size up. For awake time and outings, our layering guide for every season covers daytime outfits.

Common Overnight Dressing Mistakes

A few habits make it easy to overdress without meaning to:

• Changing the outfit but keeping the winter bag. When the weather warms, drop the bag's TOG first.

• Leaving the bag out of your layer count. Its TOG adds to everything underneath.

• Socks with a footed onesie on a mild night. The suit already covers the feet.

• A hat or bonnet still on after a pram or car nap.

• A blanket over the top of a sleeping bag. If your baby feels cool, add a layer under the bag.

• Judging warmth by cold hands at the 2am feed. Check the tummy instead.

• Dressing a wrapped baby the same as an unwrapped one. The wrap counts as a layer.

Frequently Asked Questions

What should a baby wear to bed in winter?

Cover your baby from neck to toes in one full-length suit or two thinner pieces, then let your bag’s chart decide between 2.5 and 3.5 TOG. Leave hats and beanies off, keep heavy bedding out of the cot, and feel your baby's tummy at the next feed.

Is 20°C too cold for a baby to sleep in?

Not usually. It’s a comfortable mild-night temperature, and long sleeves under a lighter 1.0 TOG bag are enough for most babies. If their tummy feels cool, add a layer under the bag. If it feels hot or clammy, take one off.

Does my baby need socks to sleep?

Not if their suit has feet, since extra socks just add warmth they don’t need. Cool feet on their own are normal and don't mean your baby is cold. On a chilly night, socks under a suit without feet are fine, as long as you judge warmth by the tummy rather than the toes.

What to Check Before Lights Out

Before you zip up the sleeping bag tonight, notice how the room feels, pick the TOG from your bag's chart, and dress your baby the way you'd dress yourself to sleep comfortably in there.

Keep the head and face uncovered, lay your baby on their back, and let a hand on the tummy at the next feed tell you whether to add or remove a layer. For the base layers themselves, our cotton baby onesies and newborn knitted rompers cover warm, mild and cold nights under whichever bag or wrap suits the room.