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My Newborn Sleeps With Their Mouth Open: Is This Normal?
Back to Baby Sleep
You're doing the 3am breathing check (for the fourth time), and there it is: your newborn, fast asleep, mouth wide open like they're mid-yawn. Adorable? Absolutely. Normal? Usually, yes. Here's why babies sleep with their mouths open, what can cause it, the signs worth a chat with your GP or health visitor, and simple ways to help your little one breathe comfortably all night.
The short answer
Most of the time, yes. A newborn sleeping with their mouth open is often just a relaxed jaw, a sleepy, milk-drunk baby or a stuffy nose. Young babies much prefer breathing through their nose, so if your baby breathes through their mouth most nights, snores loudly, or seems to pause or struggle when breathing, it's worth speaking to your GP.
Why Newborns Sleep With Their Mouths Open
Newborns are natural nose breathers. As The Lullaby Trust explains, young babies often breathe through their noses, which is one reason it's so important to keep their whole face clear when they sleep.
So why the open mouth? Often it's simple relaxation. Once your baby drifts off, their jaw muscles soften and their mouth can fall open, especially after a big feed. Plenty of babies nod off mid-feed and stay in latch position long after the milk has stopped. Others are just a bit snuffly. Newborn nasal passages are tiny, so even a little mucus can make nose breathing harder work.
The odd open-mouthed snooze is nothing to worry about. It's when mouth breathing happens most nights, alongside other signs, that it's worth a closer look.
When Do Newborns Breathe Through Their Mouth?
Newborns can breathe through their mouths when they need to, like when they're crying or their nose is blocked, but given the choice they'll use their nose. Between about 4 and 6 months, as their airway grows and changes, babies start to breathe through their mouths more easily too. By around 12 months, their breathing pattern is much closer to yours.
Common Reasons And Causes
Most of the time, a baby sleeping with their mouth open has a simple, harmless explanation. Common causes include:
- A blocked or stuffy nose. Colds and mucus can make nose breathing tricky, so your baby switches to their mouth for a while.
- A relaxed jaw. Once your baby is asleep, their muscles soften and their mouth can naturally fall open.
- Dozing off during a feed. Babies who fall asleep on the breast or bottle often stay open-mouthed for a little while after.
- Allergies. Hay fever and other long-term allergies can keep the nose congested, even without a cold.
- Enlarged adenoids or tonsils. These soft lumps of tissue at the back of the nose and throat can narrow the upper airway. They're a more common cause in toddlers and young children than in newborns.
- The shape of their airway. Occasionally, the structure of a baby's face or airway makes nose breathing harder. Your GP can take a look if you're unsure.
Even when there's a reason behind it, mouth breathing on its own usually isn't harmful. It's still worth keeping an eye on, especially if it hangs around after a cold has cleared.
When To Be Concerned About Mouth Breathing And Baby Sleep
You know your baby best, so trust your instincts. Speak to your GP or health visitor if your baby:
- Breathes through their mouth most nights, even without a cold
- Snores loudly or regularly
- Has pauses in breathing, or seems to gasp, choke or snort in their sleep
- Is very restless or sweaty when sleeping
- Finds feeding hard work or tires quickly during feeds
- Seems unusually tired or sleepy during the day
According to the NHS, loud snoring with pauses in breathing, restless sleep and mouth breathing can be signs of obstructive sleep apnoea (OSA), where the upper airway narrows or becomes blocked during sleep. Most children who snore don't have OSA, and it's treatable. A short video of your baby sleeping can really help your GP, who can refer you to a specialist if needed.
Call 999 or go to A&E if your baby is having difficulty breathing or is breathing very fast, has blue, grey or pale lips or skin, or is difficult to wake. If your baby is under 3 months old with a temperature of 38°C or higher, get medical help urgently. The NHS has the full list of signs to look out for.
Tips To Help Babies Breathe Comfortably While Sleeping
A few small habits can help your baby breathe easy, day and night:
- Keep their nose clear. Gently wipe away any mucus. Saline nose drops can help loosen a blocked nose; ask your pharmacist which product suits your baby's age. Decongestant medicines aren't suitable for young children.
- Go gently with feeds. A blocked nose makes feeding hard work, so your baby may take smaller feeds and wake sooner. Give them time and plenty of little breaks.
- Always sleep them on their back, on a firm, flat surface. It's tempting to prop up a congested baby, but sleeping in a sitting or raised position can let their chin drop to their chest and narrow their airway. Our safer sleep guide covers the basics.
- Keep their head and face uncovered. No loose bedding, pillows or soft toys in the cot, so air can flow freely.
- Keep their sleep space smoke-free. Smoke can irritate little airways, so keep it well away from your baby, before and after birth.
- Dress for the room. Aim for comfortably warm, not toasty. Feel their chest or the back of their neck to check, and see our guide to signs your baby is too hot or cold.
Sleepwear won't clear a stuffy nose, but it can help your baby stay comfortable while their body does its thing. Our Swaddle Up™ keeps their head and face clear, comes in a range of TOGs for every season, and lets them sleep in the arms-up position babies naturally love. Choose a TOG that suits your room, and you're set. It's how we've been helping little ones Love to Dream since 2008.
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FAQs About Babies Sleeping With Their Mouth Open
Is it bad for my baby to sleep with their mouth open?
Usually not. An open mouth during sleep is often just a relaxed jaw or a stuffy nose. If your baby breathes through their mouth most nights, snores loudly, or seems to pause or struggle when breathing, speak to your GP.
What can I do if my baby's nose is frequently congested?
Gently wipe away mucus, try saline nose drops (your pharmacist can recommend one for your baby's age) and give feeds a little extra time. Keep sleeping them on their back on a firm, flat surface. If their nose is often blocked even without a cold, or it's getting in the way of feeding or sleep, see your GP, as allergies or enlarged adenoids can be behind it.
Can mouth breathing affect my baby's development?
Occasional mouth breathing won't. When it's linked to ongoing sleep problems like obstructive sleep apnoea, broken sleep can affect a child's mood, behaviour, concentration and learning. That's why persistent mouth breathing is worth getting checked. The good news: the causes are usually treatable.
Is it normal for my baby to snore?
Light, snuffly snoring is common, especially when your baby has a cold. Loud or regular snoring, particularly with mouth breathing, gasping or pauses in breathing, is worth a chat with your GP.
Should I close my baby's mouth while they sleep?
No need. Gently closing their mouth won't change how they breathe, and you should never use anything that covers their mouth or face. Simply lay your baby on their back on a firm, flat surface with their head and face uncovered. If the mouth breathing continues, ask your GP.
Key takeaway
A newborn sleeping with their mouth open is usually just a relaxed, sleepy baby or a stuffy nose. Keep their nose clear, always sleep them on their back on a firm, flat surface, and dress them comfortably for the room. If mouth breathing happens most nights, or comes with loud snoring, pauses in breathing or tricky feeds, speak to your GP. You know your baby best.
Looking for more sleep support? Explore our baby sleep blog for expert tips from newborn days to big kid beds.