A TIKTOK video has exposed why most adult mattresses are too dangerous for sleeping babies.
It serves as a warning to parents that infants must always be put to bed on a firm mattress designed for cots.
Babies are at higher risk of suffocation on an adult mattressCredit: Alamy
TikTok user Melissa, a “certified infant and child sleep consultant” who goes by BabySleepCode, explained that when a baby is eight weeks old, they weigh around 5kg (11lbs), and at five months old they are 7kg (15lbs).
The Aussie-based expert said: “When sleeping on a cot mattress that meets Australian standards, there will be no indent around the baby, and any risk of rebreathing is low”.
Using dumbbells to reflect the weight of a baby, the creator showed how the weights remain flat on a firm cot mattress.
The video then said “imagine that same eight week old on this medium-firm adult mattress”, while showing the weight of the dumbbells sinking into the middle of the bed.
“Rebreathing”, mentioned in the video, is when a baby breathes in its own exhaled breath, and therefore more carbon dioxide and less oxygen.
If the baby does not wake up or respond appropriately, it can lead to death.
The tragic event can happen when the baby lies on a soft surface and the indent of its head creates a dip.
This can also lead to suffocation.

TikTok user BabySleepCode used dumbbells to show how a baby, weighing 5kg (11lbs), would not sink into a firm baby mattress (pictured)Credit: TikTok BabySleepCode

But on a soft adult mattress, the baby’s head can sink into the mattress, causing an indent, which raises the risk of rebreathing and suffocationCredit: TikTok BabySleepCode
A soft mattress is also a key risk factor for sudden infant death syndrome (SIDS) – a tragic cause of death in more than 200 babies every year in the UK.
Also known as “cot death”, it happens when a seemingly healthy baby dies for no explained reason.
But soft matresses, blankets, and co-sleeping, are all leading factors linked to SIDS.
Kate Holmes, Head of Support and Information at The Lullaby Trust, which raises awareness of SIDS, said: “Soft mattresses are known to increase the risk of SIDS because they can cause babies to become too hot.
“A baby’s mattress should be firm enough so that when they’ve placed on it their head does not sink in more than a few millimetres.
“The same advice applies to an adult mattress if parents chose to bedshare with their baby.
“If bedsharing then an adult mattress should also be firm and flat.”
Ms Holmes also warned that co-sleeping can be dangerous for your baby if a parent smokes (even if not in the bedroom), has taken drugs or medications, your baby is preamture or born at low weight.
The TikTok video said babies can roll on their sides and tummy from eight weeks old.
But the Lullaby Trust says a baby can roll both ways at around five months. But before then, parents are advised to gently roll them back.
Ms Holmes said: “Once a baby can roll both ways, approximately five months, and may sleep on their tummy, they can tilt their face to one side, so breathability isn’t important for a mattress – firm, flat and waterproof is.
“A baby won’t get too hot if they are sleeping on a firm, flat mattress with no raised edges.”
A report from The Lullaby Trust explained that one US study over two years found that if a baby’s head sinks one inch or more into a soft surface, they have a five-fold increase in the risk of SIDS.
With the addition of a baby sleeping on their front, the risk was 21-fold higher.
Another study in New Zealand found that soft cot mattresses raised the risks of SIDS by 2-fold.
Studies have also shown the risk of second-hand baby mattresses.
The Lullaby Trust says for the first six months of a baby’s life, they should sleep on their own sleep surface in the same room as their parent.
A moses basket or cot is the safest place.
It urges to look for products in the shop and online that comply with British Standards, and always read the manufacturer’s instructions to make sure you are using it in the correct way.


Its guide for choosing bedding says: “When checking a product is safe for baby to sleep on, remember the simple rule: firm, flat and waterproof.”
The NHS warns to never share a bed with your baby to avoid the higher risk of SIDS.
How to prevent sudden infant death syndrome
The NHS says although the cause of SIDS is not fully understood, there are a number of things you can do to reduce the risk.
These are:
- always place your baby on their back to sleep (once your baby is old enough to roll over, there’s no need to worry if they turn onto their tummy or side while sleeping)
- place your baby in the “feet to foot” position – with their feet touching the end of the cot, Moses basket, or pram
- keep your baby’s head uncovered – their blanket should be tucked in no higher than their shoulders
- let your baby sleep in a cot or Moses basket in the same room as you for the first 6 months
- use a baby mattress that’s firm, flat, well-fitting, clean and waterproof on the outside – cover the mattress with a single sheet
- do not use duvets, quilts, baby nests, wedges, bedding rolls or pillows
- breastfeed your baby, if you can
Do not:
- smoke during pregnancy or let anyone smoke in the same room as your baby – both before and after birth
- sleep on a bed, sofa or armchair with your baby
- share a bed with your baby if you or your partner smoke or take drugs, or if you’ve been drinking alcohol
- let your baby get too hot or too cold – a room temperature of 16C to 20C, with light bedding or a lightweight baby sleeping bag, will provide a comfortable sleeping environment for your baby