Lots of babies and toddlers wake with damp hair or a sweaty head, and on its own that is usually nothing to worry about. The Children's Hospital of Philadelphia notes that many children sweat while they sleep and some simply sweat more than others. What matters is whether your baby is too hot, because overheating raises the risk of sudden infant death syndrome (SIDS). Feel their chest or the back of their neck, take a layer off if the skin is hot or sweaty, and keep their head and face uncovered. Sweating that comes with a fever, or with getting out of breath during feeds, is a different matter and needs a doctor.
Why do babies sweat in their sleep?
Babies are still learning to manage their body temperature. The NHS page on heat rash says babies can't regulate their temperature as well as older children and adults. Red Nose in Australia says babies regulate their temperature through their head and face, which is why keeping both uncovered matters so much.
The most common reason for a sweaty baby is simply being too warm. The NHS SIDS page says babies can overheat because of too much bedding or clothing, or because the room is too hot. Typical culprits are:
- an extra layer or a sleeping bag that's too warm for the room
- a hat, hood or beanie indoors
- a duvet, quilt or duvet, or bedding tucked too high
- a cot next to a radiator or heater, or in direct sun
- a warm night, or heating left on high
Some babies just sweat more than others, even when they're dressed sensibly. And sometimes sweating is a sign of illness, most often a fever (see below).
Is a sweaty baby at higher risk of SIDS?
Sweating isn't dangerous in itself, but it is a sign your baby may be too hot, and overheating is a known SIDS risk factor. The NHS says overheating can increase the risk of SIDS, and the Lullaby Trust says the risk is higher in babies who get too hot. In the US, the AAP's safe sleep guide says the same and lists sweating, a hot chest and flushed skin as signs to check for. NICHD Safe to Sleep also names sweating and a chest that feels hot to the touch as signs a baby is too hot.
So treat a sweaty baby as a cue to check and adjust, rather than something to wait out. The other safe-sleep basics apply to every sleep: on the back, on a firm, flat mattress, in their own cot or bassinet in your room for at least the first 6 months, with nothing soft or loose in the cot. See safe sleep.
How do I check if my baby is too hot?
Don't go by their hands and feet, which are usually cooler than the rest of the body. Red Nose in Australia says to feel your baby's tummy, which should feel warm; the NHS and the Lullaby Trust say to feel the chest or the back of the neck. Cool hands and feet are normal.
| What you feel or see | What it usually means | What to do |
|---|---|---|
| Warm, dry chest, neck or tummy | Comfortable | Nothing |
| Hot or sweaty chest, neck or tummy | Too warm | Remove a layer or some bedding |
| Damp hair, flushed cheeks, heat rash | Too warm | Remove layers, cool the room |
| Cool tummy or chest | A bit cold | Add a light layer of clothing |
| Cold, clammy skin, or pale or blotchy | Possibly very unwell | Call 999 now |
The AAP's swaddling advice lists sweating, damp hair, flushed cheeks, heat rash and fast breathing as signs of overheating. If your baby is breathing very fast or working hard to breathe, don't just take a layer off: call 999.
The last row matters. The NHS list of urgent signs includes skin that feels cold or damp (clammy) to touch, and blue, grey, pale or blotchy skin, lips or tongue. Warm and sweaty usually means too many layers; cold and clammy does not.
How should I dress my baby so they don't overheat?
Dress your baby for the room they sleep in. The Lullaby Trust and the NHS suggest a room of 16–20°C, checked with a room thermometer. Red Nose in Australia doesn't recommend a specific room temperature and says to dress your baby as you would dress yourself for the room, while the AAP suggests one layer more than you're wearing. Baby room temperature compares these in detail, and dressing your baby for sleep has outfits by temperature and how to choose a sleeping bag's tog.
A few rules make the biggest difference to a sweaty sleeper:
- No hats indoors. The NHS, the Lullaby Trust, the AAP and NICHD all say to take hats off inside.
- Head and face uncovered. Australia's Red Nose's sleeping bag advice is a bag fitted across the neck and chest, with arms out and no hood.
- No duvets or quilts. The Lullaby Trust says babies shouldn't sleep under a duvet or quilt.
- Keep heat sources away. The NHS says never to let your baby sleep with a hot water bottle or electric blanket, next to a radiator, heater or fire, or in direct sunlight.
What should I do if my baby is sweaty in their sleep?
- Feel their chest, back of the neck or tummy. If it is warm and dry, leave them be.
- Remove a layer if they feel hot or sweaty. The NHS and the Lullaby Trust say to take off one or more layers of clothing or bedding. You don't need to strip them down.
- Check their head and face. Take off any hat or hood, and make sure bedding is no higher than their chest or shoulders.
- Cool the room if it's warm. The Lullaby Trust suggests opening the door and a window if it's safe, and using a fan that isn't aimed at your baby.
- Offer a feed if they wake. Australia's Red Nose suggests offering fluids once you've cooled a flushed, clammy baby.
- Change a soaked sleepsuit for something lighter and dry, then put them back down on their back.
- Check their temperature if they still feel hot after you've removed layers, or seem unwell. A fever is a different problem from overdressing.
If you're tempted to add a layer "just in case" on a cool night, check your baby first. The Lullaby Trust says it is rarely necessary to keep the heating on all night.
Could sweating at night be a sign my baby is unwell?
Fever
The NHS fever page says a high temperature is 38°C or more, and lists feeling hotter than usual on the back or chest and feeling sweaty as signs of a fever. It says not to cover a feverish child in too many clothes or bedclothes. The Royal Children's Hospital Melbourne suggests light clothes and extra breastfeeds or bottle feeds for babies under 6 months, and the Lullaby Trust says not to wrap an unwell baby up more than usual. Age changes how urgent a fever is; see fever in babies.
Sweating or breathlessness during feeds
The Children's Hospital of Philadelphia lists getting out of breath with feeds and getting sweaty with feeds among the signs in babies that can point to a heart problem. It stresses that in most cases children with these symptoms don't have one, but says to tell your doctor so they can examine your baby. The NHS congenital heart disease page lists difficulty feeding, slow weight gain, shortness of breath and being sweatier than usual with cool, clammy skin, and advises urgent help if you think your child has symptoms. So if your baby gets sweaty and breathless, tires or stops often during feeds, or isn't gaining weight, get medical help today. Call 999 if they are struggling to breathe, their lips or skin turn blue or grey, or their skin feels cold and clammy.
Heat rash
Heavy sweating can block sweat glands. The NHS describes heat rash as small, raised, prickly spots that can look red on white skin and grey or white on brown or black skin. It suggests loose cotton clothing, lightweight bedding and keeping the skin cool, and seeing a GP if the rash isn't improving after a few days or you're worried.
Heat stress on hot days
Red Nose in Australia says babies heat up faster than adults and don't sweat as much. Its summer advice describes heat stress as unusual fussiness, listlessness or irritability, pale, clammy skin that becomes hot and flushed, and heavy sweating at first that lessens as the baby overheats. So a hot baby who has stopped sweating isn't necessarily cooler. Move them somewhere cooler, remove layers and offer a feed, and call 999 if they are listless, floppy, hard to wake or breathing very fast. See hot weather.
Snoring
If your child sweats at night and also snores most nights, or seems to gasp or pause in their sleep, the AAP's sleep apnoea guide says to let your child's doctor know about frequent snoring and breathing problems at night. See baby sleeping with mouth open.
What's worth noting down?
If sweating keeps happening, a few nights of notes help you and your GP or health visitor see the pattern: the room temperature, what your baby wore and slept in, whether they were sweaty during sleep or during feeds, and any temperature readings. Note feeding too, such as long or breathless feeds and wet nappies.
When to get help
Call 999 now also for a weak, high-pitched or continuous cry, a rash that doesn't fade when you press a glass on it, a seizure, a temperature below 36°C, or no wet nappy or wee for 12 hours. These are on the NHS list of urgent signs.
Get medical help today (same-day GP, after-hours doctor or NHS 111) if your baby:
- gets sweaty and out of breath during feeds, tires quickly or stops feeding often
- is refusing feeds or feeding much less than usual, or has fewer wet nappies
- has had a fever for 5 days or more
- still feels hot after you've removed layers and seems unwell
Talk to your GP or health visitor if your baby sweats heavily most nights even when lightly dressed in a cool room, if heat rash isn't improving after a few days, or soon if your child snores most nights.
