Key highlights
- Feel the chest or back of the neck, not hands or feet.
- Damp hair, flushed cheeks and rapid breathing are early warnings.
- Aim for a room between 16–20°C (61–68°F).
- Remove a layer before adding a fan or opening a window.
- Never use hats indoors for sleep.
Overheating has been linked by The Lullaby Trust and Red Nose Australia to an increased risk of SIDS, so learning to recognise the signs quickly gives you real peace of mind at bedtime. The good news is that babies are surprisingly good at telling us when they're too warm — you just have to know where to look.
The most reliable signs
The NHS and NCT both recommend feeling your baby's chest, tummy or the back of the neck. If the skin feels hot, sweaty or clammy, your baby is almost certainly too warm. Hands and feet are not a reliable guide — they naturally run cooler because babies send blood to their core first.
- Sweating or damp hair, especially at the back of the head
- Flushed cheeks or a red, blotchy face
- Rapid or shallow breathing during sleep
- A hot chest or back of the neck
- Restlessness, unusual fussiness or frequent waking
- In extreme cases, a raised temperature or lethargy
Why overheating matters
The Lullaby Trust highlights overheating as one of the modifiable risk factors for sudden infant death. Babies can't regulate their temperature as effectively as adults, and a room that feels comfortable to a grown-up in pyjamas can be too warm for a baby in a sleep sack and layers. Red Nose Australia adds that thick coats, snowsuits and car-seat inserts can cause rapid overheating in minutes, particularly indoors or in a warm car.
How to cool your baby down safely
If your baby feels hot, start by removing one layer — often just taking off the sleepsuit and leaving a vest under the sleep sack is enough. Then look at the room itself: close blinds during the day, open a window in the evening, or use a fan aimed away from the cot to move air around the room. In a heatwave, moving your baby to the coolest room in the house is safer than reaching for a lower TOG you don't own.
Offer extra feeds — breastfed babies may want the breast more frequently, and formula-fed babies over six months can be offered cooled boiled water. Never cover your baby's face, and never use a hat indoors: babies lose a lot of heat through their heads, and hats are one of the most common causes of overheating during sleep.
Quick rule of thumb
Dress your baby in one fewer light layer than you'd wear yourself to sleep comfortably in the same room. When in doubt, check the chest — not the hands.
When to seek advice
If your baby is unusually drowsy, difficult to rouse, has a temperature above 38°C (under three months) or 39°C (three to six months), or you're worried about their breathing, contact your GP, health visitor or NHS 111 — or your local emergency number. Trust your instincts: you know your baby best.