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Safe baby sleep: how to lower the risk of SIDS

Last verified: July 9, 2026

The short answer

  • Back to sleep, for every nap and every night
  • Firm flat mattress, cot clear of everything but a fitted sheet
  • Your room, a separate cot, for the first 6 months

That combination does more to lower the risk of SIDS than anything else. Below is each step, plus the honest version of the one topic where advice splits: co-sleeping.

Illustration of a baby cot under a crescent moon

A note before we start. This is a heavy subject, and reading about it can feel frightening. SIDS is rare. The steps below are simple, and most of them you are probably doing already.

What SIDS is, and who is most at risk

Sudden infant death syndrome is the sudden and unexplained death of an apparently healthy baby under 12 months old. It used to be called cot death. It is rare, but it does still happen, and no one knows exactly what causes it (NHS: SIDS).

Because the cause is unknown, there is no guaranteed way to prevent it. What research does show is that a safe sleep setup lowers the risk, and it also prevents the accidental suffocation and strangulation that we do understand (AAP: How to keep your sleeping baby safe).

SIDS is more likely in the first 6 months, though it can affect babies up to a year. Babies born before 37 weeks or under 2.5kg are at higher risk, which is why twins and other multiples are too. If your baby was born early, the NHS says to follow safe sleep advice for a full year from their due date, not their birth date.

Back sleeping, every single time

Babies who sleep on their backs are far less likely to die suddenly than babies on their fronts or sides. The side position is not safe, because a baby can roll from their side onto their front. So it is back, for every nap and every night.

A common worry is choking. Both the NHS and the AAP are clear that a baby’s airway and gag reflex prevent this. The AAP adds that even babies with reflux should sleep flat on their backs. The NHS uses the feet-to-foot position: lay your baby with their feet at the bottom of the cot or Moses basket, so they cannot wriggle down under the covers.

Once your baby can roll both ways on their own, front to back and back to front, you do not need to keep turning them over. Just make sure the cot is clear, which is the next point.

A firm, flat, empty sleep space

The mattress should be firm and flat, one that does not dip when your baby lies on it. The AAP says any surface tilted more than 10 degrees is not safe, which rules out inclined sleepers.

Keep the cot clear. The NHS says no pillows, no duvets, no cot bumpers, no loose blankets, no soft toys, and nothing meant to hold your baby in place like pods or nests. The AAP adds weighted blankets and weighted swaddles to that list. A fitted sheet, and nothing else. If you worry about your baby being cold, dress them in a layer more than you are wearing, or use a baby sleeping bag, rather than adding bedding.

Room sharing, not bed sharing

Put your baby to sleep in their own cot, Moses basket or crib, in your room, for at least the first 6 months. Both organisations agree on this, and the reason is strong.

up to 50% lower risk of SIDS from room sharing instead of bed sharing American Academy of Pediatrics

Room sharing also makes night feeds and comforting easier, without the risks of having your baby in the bed itself.

The honest part: co-sleeping

Here the advice genuinely differs, and you deserve to hear both versions rather than one dressed up as the only truth.

The AAP does not recommend bed sharing under any circumstances. Its position is that the safest place is a separate surface, full stop. It notes the risk of a sleep-related death is up to 67 times higher when a baby sleeps with someone on a sofa or armchair, and it says if you bring your baby into your bed to feed, move them back to their own space before you sleep.

The NHS takes a harm-reduction line. It also says the safest place is a separate cot, but it accepts that some parents will co-sleep, and so it gives rules to make it less dangerous: a firm flat mattress, baby on their back, pillows and blankets kept away, no swaddling, no other children or pets in the bed, and never leaving the baby alone in an adult bed.

Where they fully agree is worth putting in bold, because these are the hard lines. Never sleep with your baby on a sofa or in an armchair. And never bed share at all if your baby was born before 37 weeks or under 2.5kg, or if you or your partner smoke, have had alcohol, or have taken drugs or any medicine that makes you drowsy. In those situations the risk is far too high.

Not too hot

Overheating raises the risk of SIDS. Keep the room between about 16 and 20C, and give your baby one layer more than you would wear, no more. Check whether they are too warm by feeling their chest or the back of their neck, not their hands or feet, which run cool normally. The AAP says skip the hat indoors once you are home from hospital. Never place a baby to sleep next to a radiator or heater, in direct sunlight, or with a hot water bottle.

The things that also help

A safe sleep space is the core, but a few other steps lower the risk further:

  • Breastfeeding, if you can. Both organisations note that breast milk protects against SIDS, and the longer you do it, the more protection it gives.
  • A pacifier at nap and bedtime. Some research links this to a lower risk, even if it falls out once your baby is asleep. If breastfeeding, wait until it is well established first. Never hang a pacifier around your baby’s neck.
  • Up-to-date vaccinations. Being current on routine jabs is linked to lower SIDS risk.
  • A smoke-free pregnancy and home. Smoking in pregnancy, and smoke around your baby afterwards, are significant risk factors. This includes vaping. If anyone in the household smokes, it is even more important not to bed share.
  • Awake tummy time, supervised, every day. It is not about sleep safety directly, but it helps motor development and prevents a flat spot on the head. The AAP suggests building up to 15 to 30 minutes a day by around 7 weeks. Our tummy time guide covers how to start and what to do if your baby hates it.

One thing to skip: home heart or oxygen monitors sold to prevent SIDS. The AAP says there is no evidence they reduce the risk, and warns against letting them give you a false sense of security in place of the steps above.

Car seats and slings

It is fine for your baby to fall asleep in a car seat while you travel, but the NHS says do not leave them in it for too long, and move them to a firm flat surface once you arrive. If you use a sling, follow the T.I.C.K.S. rule: tight, in view at all times, close enough to kiss, keep their chin off their chest, and their back supported.

When to call 999

Call 999 now

Call an ambulance straight away if your baby:

  • stops breathing or will not wake up
  • is struggling to breathe
  • is stiff, shaking or jerking, which may be a seizure
  • has lips, face or skin that suddenly turn pale, blue or grey, which on brown or black skin may show first on the palms or soles
  • is limp, floppy, or not responding like they normally do
Call your GP or 111

For anything that worries you short of an emergency, contact your GP or NHS 111. As always, your own concern is reason enough to ask.

If you have lost a baby to SIDS, or you are frightened and want to talk to someone, The Lullaby Trust runs a helpline on 0808 802 6868 and offers bereavement support.

Keep reading

Sources

*Peanutbean provides general information for educational purposes only. It is not medical advice. Every baby develops

Common questions

What is the safest way for a baby to sleep?

On their back, for every sleep, day and night, on a firm flat mattress in a cot that is clear of pillows, bumpers, loose blankets and soft toys, in your room for at least the first 6 months. Back sleeping is the single most important step.

Is co-sleeping safe?

The safest place for a baby is a separate cot in your room. The AAP advises against bed sharing in any circumstance, while the NHS gives rules to make it safer if you do it. Both agree on two hard lines: never sleep with your baby on a sofa or armchair, and never bed share if your baby was premature or low birth weight, or if anyone in the bed has smoked, drunk alcohol, or taken drugs or sedating medicine.

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Peanutbean provides general information for educational purposes only. It is not medical advice. Every baby develops at their own pace. Always talk to your pediatrician about your child's health.