Signs Your Baby Is Too Hot While Sleeping (And How To Cool Them Down)

When my daughter Olympia was born in July, it was in the middle of a UK heatwave. I was completely overwhelmed with worry about keeping her cool. I remember waking up throughout the night to check her temperature for the hundredth time, and obsessively Googling symptoms of a newborn overheating.

Signs of Infant Overheating at Night

Understanding infant overheating symptoms can help ease some of those anxious middle-of-the-night checks. Babies can’t regulate their temperature like adults, so it’s up to us to look out for subtle cues. Some common signs your baby is too hot while sleeping include:

• Feeling hot to the touch (especially on the chest, back, or neck)

• Flushed or red cheeks

• Sweating or damp hair (though some overheated babies don’t sweat at all)

• Fussiness or difficulty settling

• Seeming unusually tired, weak, or out of sorts

• Vomiting or signs of nausea

• A faster-than-usual heart rate

  
  

These are signs your baby is too hot while sleeping, but they might not all show up at once. 

How to Tell If Baby Is Too Hot (or Cold)

When you're wondering how to tell if your baby is too hot, your hand can be a surprisingly useful tool. Gently place the back of your hand on the back of your baby’s neck or chest, which will give you an idea of your little one’s core temperature. If their skin feels hot, clammy, or sweaty, they might be too warm.

You can also use a digital thermometer for a more accurate reading. For newborns, rectal readings tend to be the most reliable, but you can also use a forehead (temporal) thermometer for a quick check. A normal baby's temperature is around 36.5°C to 37.5°C (97.7°F to 99.5°F). If your baby has a temperature of 38°C (100.4°F) or higher, this is considered a fever. 

You can also use a thermometer or put your hand on their back to check if your baby is too cold. Most babies will cry if they get too cold throughout the night and you can combat this easily by adding additional layers. 

Will Your Baby Cry If Too Hot at Night?

There’s a saying I heard again and again while pregnant that haunted me:

“Cold babies cry, hot babies die.” 

It sounds brutal, but it’s something that sticks with you when you're trying to make sure your baby is safe at night. The idea is that a cold baby will likely fuss and let you know, but an overheated baby might become lethargic or unresponsive instead. It's not always true across the board, but it is a powerful reminder that overheating can be silent and subtle. That’s why it’s so important to keep an eye on baby's temperature and ensure they’re as cool as possible during hot nights. 

Tips to Keep Your Baby Cool at Night

Keeping your baby’s room cool can feel like a mission in the middle of a heatwave, especially in UK houses, which are actually designed to insulate and keep the home warm. We recommend using a room thermometer to keep an eye on the temperature of the room your baby sleeps in.

We used the Tommee Tippee Gro Egg and while it was incredibly helpful, I’ll be honest—it can be a bit anxiety-inducing. Seeing that glaring red light at 3 am triggered more stress than reassurance some nights. If you're someone who fixates on numbers, it might not be the best fit—or you might prefer a thermometer without a visual display.

Here are some other practical ways to keep your baby cool:

• Dress them lightly: A short-sleeved bodysuit or just a nappy may be enough on hot nights. You can find a room temperature guide (like the one below) to help you decide on appropriate clothing. Sometimes I would dress baby in just a nappy and as it cooled down more during the night, I’d add a vest during her next feed.

  
  

  

  
  

• Use breathable fabrics: Choose muslin swaddles or 0.2–0.5 TOG sleeping bags, again a sleeping tog guide can advise you on the best tog for higher temperatures.

  
  

• Create airflow: Use a fan placed away from your baby to keep air circulating. Ensure the fan is not blowing directly on your baby’s sleeping area. You can also open up windows at night and create a cross-breeze. Just make sure your baby is not right by a window or they might get too cold.

  
  

• Keep curtains and windows closed during the day to block out the sun and reduce heat build-up. You can then open your windows at night once the temperature has dropped.

  
  

• Keep baby hydrated: Offer extra feeds during hot spells. If you’re breastfeeding, you may notice your supply will naturally become more watery to help hydrate baby more. 

  
  

• Have baby sleep in a cooler room: On really hot nights, we slept downstairs with our little one in the Moses basket, as our front room was cooler than upstairs. It might be uncomfortable, but it’s only temporary and worth the sacrifice to keep your baby safe.

  
  

I worried so much about getting the temperature right during those warm months and it was particularly scary having a newborn. But learning what to look for and knowing how to dress a baby for hotter temperatures made all the difference. Luckily, UK hot weather is often very short-lived, so before you know it the temperature will have dropped back down again.