What should you cover a newborn with at night?
For most newborns, there is no need to cover the baby with a separate loose blanket. Appropriate clothing and a properly fitted sleep sack are a straightforward alternative.
The key distinction is that a sleep sack is worn by the baby. It does not move freely around the cot in the way a blanket can.
The AAP recommends keeping blankets, comforters, pillows, toys, bumper pads and other soft objects out of an infant's sleep space. If extra warmth is needed, parents can use suitable clothing layers or a wearable blanket.
Why are loose blankets discouraged?
Loose bedding can move toward a baby's face and can also contribute to overheating.
A newborn cannot reliably move a blanket away if it covers the nose or mouth. For that reason, the AAP's safer-sleep approach is based on a clear sleep surface: a firm, flat mattress with a fitted sheet and no loose bedding.
There are some regional differences in guidance. The NHS allows a lightweight cellular blanket when it is used correctly: the baby is placed on their back with their feet near the foot of the cot, and the blanket is firmly tucked in and reaches no higher than the shoulders. The NHS also presents a well-fitting baby sleeping bag as an effective way to avoid a baby wriggling underneath bedding.
For parents who want the simplest possible setup, using a sleep sack and keeping loose bedding out of the cot removes one variable.
How should a newborn sleep sack fit?
A sleep sack should fit closely enough around the shoulders and neck that the baby's head cannot slip inside it.
Before using one, check:
the manufacturer's minimum weight or height;
the neck opening;
the shoulder fit;
whether the product is suitable for the baby's age;
the TOG rating;
the clothing recommendations for that TOG;
that there is no hood covering the head.
NHS guidance specifically warns that the shoulder opening must fit correctly so that a baby's head cannot slip down into the bag.
A larger sleep sack is not automatically better. Choosing a size for a child to “grow into” can create an unsafe fit around the upper body.
What does TOG mean on a baby sleep sack?
TOG is a measure of thermal insulation. In simple terms, a higher TOG usually provides more warmth.
The NHS gives the following general examples:
2.5 TOG: around 16–20°C;
1.0 TOG: around 20–24°C;
0.5 TOG: around 24–27°C.
These figures are useful as orientation rather than a substitute for the product's own instructions. Different materials and designs can behave differently.
What should a newborn wear under a sleep sack?
The answer depends on room temperature and the warmth of the sleep sack. There is no single outfit that works in every season.
The AAP provides a useful rule of thumb: babies generally need no more than one additional layer compared with what an adult would wear comfortably in the same environment.
That could mean:
lighter clothing under the sleep sack in a warm room;
a sleepsuit or bodysuit plus an appropriate sleep sack in cooler conditions;
very minimal layers during hot weather.
Always treat the clothes and sleep sack as one thermal system rather than choosing each item independently.
What room temperature is best for a newborn?
There is no single temperature that makes sleep safe on its own. Preventing overheating and adjusting clothing to the actual room conditions are more important than chasing an exact number.
Guidelines vary slightly. German public-health information suggests around 18°C for infant sleep, while NHS TOG guidance covers common room temperatures from approximately 16°C upward. The AAP focuses more broadly on keeping the room comfortable and avoiding excessive clothing or bedding.
A room thermometer can make decisions easier, especially when using TOG-rated sleepwear.
How can you tell whether a baby is overheating?
Sweating, a hot chest and flushed skin are warning signs that a baby may be too warm.
The AAP advises parents to look for these signs and notes that babies do not need to wear hats indoors after returning home from the hospital.
Cold hands or feet alone do not necessarily mean the baby needs another heavy layer.
If the baby's chest feels unusually hot or the baby is sweating, remove a layer and reassess the environment.
Is swaddling the same as using a sleep sack?
No. Swaddling restricts arm movement, while a conventional sleep sack generally leaves the arms free. The safety rules are therefore different.
The AAP states that swaddling has not been shown to reduce SIDS risk. A swaddled baby must always be placed on their back, the wrap must not restrict breathing or hip movement, and swaddling should stop when the baby begins showing signs of attempting to roll. Weighted swaddles and weighted sleep products are not recommended.
A standard non-weighted sleep sack with free arms can therefore be easier to use as a baby develops.
What should be inside a newborn's cot?
Very little. A safer infant sleep space is intentionally simple.
The core setup is:
a firm, flat mattress;
a tightly fitted sheet;
the baby placed on their back;
no pillow;
no soft toys;
no bumper pads;
no loose blankets under the AAP approach;
no weighted sleep products.
The AAP also states that sleep surfaces inclined by more than 10 degrees are not considered safe infant sleep surfaces.
The material of the mattress is less important than its firmness, flatness, fit and compliance with the relevant safety requirements.
Sleep sack or blanket: which is the better option?
For parents who want the least complicated setup, a well-fitting sleep sack is usually the easier choice.
A sleep sack:
stays with the baby;
does not need to be tucked under the mattress;
can be selected by warmth rating;
helps keep loose material away from the face.
A blanket:
is permitted under some European guidance when positioned correctly;
must remain firmly tucked in;
should not reach above the shoulders;
should not be repeatedly folded, which increases insulation.
The important point is not that every blanket is inherently dangerous in every context. It is that eliminating loose bedding creates a simpler sleep environment with fewer positioning variables.
Common mistakes when keeping a newborn warm at night
Most mistakes come from adding unnecessary warmth or extra objects to the cot.
Common examples include:
combining a warm sleep sack with a thick duvet;
putting a hat on a baby for normal indoor sleep;
using a pillow for a newborn;
adding bumpers, nests or soft objects around the head;
buying an oversized sleep sack;
using weighted blankets or weighted sleep sacks;
adding layers without checking the room temperature;
assuming cold hands always mean the baby is cold.
A safer sleep setup does not need to look heavily padded or cosy. In infant sleep, simplicity is a feature.
Conclusion
When deciding what to cover a newborn with during sleep, the simplest answer is often nothing loose. Dress the baby appropriately for the room and use a correctly fitted sleep sack when an additional layer is needed.
The larger safety picture matters even more: place the baby on their back, use a firm and flat mattress, keep the head uncovered, remove soft objects from the sleep space and avoid overheating.
For premature babies, babies with low birth weight or children with medical conditions affecting breathing or temperature regulation, individual medical advice should take priority over general sleep guidance.
FAQ
Can a newborn sleep without a blanket?
Yes. A newborn can sleep without a loose blanket when dressed appropriately for the room. The AAP recommends clothing layers or a wearable blanket when extra warmth is needed.
Are sleep sacks safe for newborns?
A correctly sized, well-fitting infant sleep sack is widely recommended as an alternative to loose bedding. The shoulder and neck openings should prevent the baby's head from slipping inside.
What TOG should a newborn sleep sack be?
It depends on room temperature and the manufacturer's instructions. As a general reference, NHS guidance lists 2.5 TOG for 16–20°C, 1.0 TOG for 20–24°C and 0.5 TOG for 24–27°C.
Can a newborn sleep under a blanket?
Guidelines vary. The AAP recommends removing loose blankets from infant sleep spaces entirely. NHS guidance permits a lightweight blanket when it is firmly tucked in below shoulder level. A sleep sack provides a simpler alternative.
Should a newborn wear a hat while sleeping?
Not for normal indoor sleep after leaving the hospital. The AAP recommends keeping the baby's head uncovered indoors and avoiding overheating.
How do I know if my newborn is too hot at night?
Sweating, a hot chest or flushed skin can indicate overheating. If these signs appear, reduce a layer and reassess the room temperature.
Can I put a blanket over a baby in a sleep sack?
Normally there is no need to add another layer of loose bedding. Clothing should be matched to the sleep sack's warmth and the room temperature. NHS guidance states that additional bedding should not be used with a sleeping bag.
