Baby Room Temperature for Sleep: The Ideal Range and What to Dress Them In

The ideal room temperature for a sleeping baby is 16–20 °C, which is the range recommended by the UK safer-sleep charity The Lullaby Trust. Babies sleep comfortably slightly cooler than many parents expect. A well-fitting sleeping bag, combined with suitable layers of clothing, can help keep your baby comfortable. The number of layers will depend on the room temperature, the sleeping bag and your baby's individual needs. To check whether your baby is too warm or too cold, feel their chest or the back of their neck, not their hands and feet.

What room temperature should a baby sleep in?

Aim for 16–20 °C in the room where your baby sleeps. Around 18 °C is a comfortable middle: a cool bedroom is the right default. For the first six months, your baby should sleep on their back, in their own clear, flat sleep space in the same room as you.

The Lullaby Trust states that the risk of sudden infant death syndrome (SIDS) is higher in babies who get too hot. That is why the advice focuses on avoiding overheating: keep the room in range, do not over-dress your baby, keep the head uncovered and do not use duvets, quilts or loose blankets.

Place the cot away from radiators, heaters and direct sunlight. In winter, keep the heating low overnight rather than warming the room above 20 °C; if the room is cooler than 16 °C, add a layer of clothing.

What should my baby sleep in at 18, 20, 22, 24 or 26 °C?

There is no official chart, because clothing, sleeping bags and babies all differ. The table below is our indicative dressing guide for Zizzz sleeping bags, not a universal prescription.

These combinations are examples, not fixed rules. Every baby is different, and the warmth of clothing varies depending on the fabric and number of layers. Always check your baby's chest or the back of their neck and adjust their clothing if necessary. If your baby feels hot or sweaty, remove a layer. If the room is colder than 16 °C, add a layer and bring the room closer to 16 °C if you can.

A sleeping bag keeps your baby warm without a loose blanket in the bed. Choose one that fits: snug at the neck and arm openings so it cannot ride up over the face, with room for the legs to kick. Our guide to choosing the right sleeping bag size explains how to measure.

How do I know if my baby is too hot or too cold at night?

Feel your baby's chest or the back of their neck. Warm and dry is right. Hot, damp or sweaty means your baby is too warm: remove a layer or switch to a lighter sleeping bag. If the skin feels cool, add a layer.

Do not rely on hands and feet. They are usually cooler than the rest of the body, and that is normal. A sweaty head on its own is common too; if you notice it often, our article on why some babies sweat so much while sleeping explains the usual causes.

Being too warm or too cold can also make a baby restless. If your baby wakes often, temperature is one of the first things to check; see also my baby keeps waking up at night.

What if the bedroom is too warm in summer?

• Dress your baby in fewer layers (see the table). In a very hot room, a light bodysuit or just a nappy may be enough, without a sleeping bag.
• Keep curtains or blinds closed during the day and open the window and door at night if it is safe to do so.
• A fan can help cool the room, but do not point it directly at your baby.
• Offer plenty of feeds. Fully breastfed babies under 6 months do not normally need extra water. Formula-fed babies may need a little cooled boiled water in hot weather, in addition to their usual feeds.

What is a normal body temperature for a baby, and when is it a fever?

A baby's normal body temperature is roughly 36.5–37.5 °C. Temperature readings vary with the time of day and the method used. If a reading seems unusually low or high, check it again with a reliable thermometer and seek medical advice if you are concerned, particularly for a newborn.

• Fever: 38 °C or higher.
• Under 3 months: a temperature of 38 °C or higher means your baby should be seen by a doctor straight away.
• 3 to 6 months: contact your paediatrician the same day for a temperature of 39 °C or higher.
• Low temperature: a reading below 36 °C in a young baby, especially one who seems unwell, should also be checked by a doctor.

A baby with a fever should not be bundled up. For practical advice, read how to dress your baby at night if they have a fever.

Why are babies more sensitive to room temperature?

Newborns cannot yet regulate their body temperature as well as adults. They have a large skin surface relative to their weight, so they lose heat quickly, and they cannot shiver effectively to warm up. At the same time, they cannot take off a layer when they get too hot. That is why the room temperature and the number of layers matter more for a baby than for an adult.

Room temperature during the day and humidity

During the day, around 20 °C is comfortable in the nursery and living areas. Keep the changing area a little warmer, because your baby is undressed there.

For humidity, a level of roughly 40–60 % is usually comfortable: very dry air can irritate the nose and throat, and persistently damp air encourages mould. Air the room regularly, especially in winter.

Zizzz sleeping bags for every room temperature

Our four-season sleeping bags have a Swisswool filling and an outer fabric of GOTS-certified organic cotton. According to our product guidance they are suited to bedrooms of about 16–22 °C. For warmer rooms, our summer sleeping bags are made of soft organic cotton without filling. Our sleeping bags are available in several sizes, from 70 cm for newborns up to 160 cm for children aged 6 to 10, so they can continue enjoying the comfort of a sleeping bag as they grow.

Browse all baby sleeping bags.

Frequently Asked Questions

What temperature should a baby's room be at night?

16–20 °C, with around 18 °C as a comfortable middle. Keep the cot away from radiators and direct sunlight, and check your baby's chest or the back of the neck to see whether they are warm enough.

What should a baby sleep in at 22 °C?

As a guide for Zizzz sleeping bags: at 22–23 °C, long-sleeved pyjamas under a summer sleeping bag; at 20–21 °C, a short-sleeved bodysuit and long-sleeved pyjamas under a four-season sleeping bag. Check the chest or the back of the neck and remove a layer if the skin feels hot or sweaty.

What should a baby sleep in at 24 or 25 °C?

As a guide for Zizzz sleeping bags: a short-sleeved bodysuit under a summer sleeping bag. From 26 °C, a short-sleeved bodysuit or a nappy alone may be enough, without a sleeping bag. Ventilate the room at night and never point a fan directly at your baby.

How do I know if my baby is too hot at night?

Feel the chest or the back of the neck. If the skin is hot, damp or sweaty, your baby is too warm: remove a layer or use a lighter sleeping bag. Cool hands and feet are normal and are not a reliable sign.

Is 36.2 °C a normal temperature for a baby?

A baby's normal temperature is generally around 36.5–37.5 °C, although readings can vary depending on how and where the temperature is measured. If you get a reading of 36.2 °C, check the temperature again using a reliable digital thermometer. If it remains low, particularly in a newborn, seek medical advice. A temperature below 36 °C can be a sign of serious illness in babies and young children.

Should my baby wear a hat to sleep?

No. Babies do not need a hat indoors. They lose heat through their head, and a hat can make them overheat.

Sources

• The Lullaby Trust – Room temperature: recommended room temperature, checking your baby, hats, hot weather and overheating.
• NHS – High temperature (fever) in children: fever thresholds, low temperatures and when to seek medical help.

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