Baby Room Temperature for Sleep

Aim for a room between about 16C and 20C, dress her for the room you actually have rather than the one you wanted, and check her by feeling her chest or the back of her neck. Not her hands, not her feet — those are cool on perfectly comfortable babies and always have been. That 16 to 20C band is not arbitrary: it is the room the 2.5 tog sleeping bag is specified for, and the whole tog scale is written from it. If your room sits above the band, the answer is fewer layers, not a warmer bag.

Overheating is the reason this is checked rather than assumed. It is one of the things safer-sleep guidance asks parents to control, which is why a subject that looks like comfort is filed under safety — and why the fix is nearly always to take something off rather than to add a device.

The band, and where it comes from

The NHS puts a baby's room at about 16C to 20C, and the tog scale on the label of every sleeping bag assumes exactly that. The bags are specified like this:

• 2.5 tog — for a room of 16 to 20C.
• 1.0 tog — for a room of 20 to 24C.
• 0.5 tog — for a room of 24 to 27C.

Read those as a single instruction rather than three: pick the bag for the temperature the room actually is. A 2.5 tog bag in a 23C bedroom is the wrong bag, however cold the night outside is, and a house that never drops below 21C in summer simply needs a lighter one for four months of the year.

Use a thermometer rather than your own judgement. A room feels different to a dressed adult standing up than it does to a baby lying still at cot height, and most people are surprised the first time they measure the difference between the landing and the corner the cot is in. Any cheap room thermometer will do; you are looking for a band, not a decimal place.

The check that takes two seconds

Slide two fingers inside the neck of her sleepsuit, onto her chest or the back of her neck. Warm is right. Hot, clammy or damp means take a layer off. Cool skin on the chest means add one.

Hands and feet are the single most common false alarm in this subject. A young baby's circulation keeps the extremities cooler than the core, so cold hands are the normal state of a warm, comfortable baby, and a parent who dresses to fix them will overdress every night. If her hands are cold and her chest is warm, nothing needs doing. The same rule holds at three in the morning when you are half awake: chest or the back of the neck, never the hands.

Signs she is too hot

The AAP's swaddling guidance lists the signs worth knowing, and they are easy to see once you know to look for them: sweating, damp hair, flushed cheeks, heat rash, and breathing faster than usual. Any of those means fewer layers and a cooler room, not a warmer blanket over the top.

The reason this gets its own paragraph on a sleep site is that overheating raises risk, which is why safer-sleep guidance treats room temperature as a thing to control rather than a matter of taste. That is also why no page here will tell you a baby who kicks her legs out is cold. She may simply be doing what babies do with their legs.

Nothing weighted goes on or over a sleeping baby, at any room temperature. Weight on the chest is not a way to keep a baby warm, and no publisher this site may cite recommends it.

Dressing by layers

Think in layers you can remove in the dark rather than in a single correct outfit. A short-sleeved bodysuit and a well-fitting sleeping bag covers most of the year in most heated homes. Colder room, add a long-sleeved bodysuit or a footed sleepsuit under the bag. Warmer room, drop to the bodysuit alone, or to a nappy and a light bag in high summer.

A sleeping bag has one advantage a blanket cannot have: it cannot ride up over her face, which is why the NHS notes bags can help. Check the neck and armholes are snug enough that she cannot slip down inside it — a bag that fits well around the shoulders is the whole safety test.

If you use a blanket instead, it goes tucked in firmly no higher than her shoulders, never doubled over, with her feet at the foot of the cot so she cannot wriggle down under it. No hats indoors: a baby loses heat through her head, and covering it while she sleeps is the fastest way to overheat her. Beyond that, the cot itself does not change with the season, and safe sleep basics covers the rest of it. Babies sleep on their back, on a firm flat mattress, in a cot clear of blankets, pillows, bumpers and soft toys, in your room for at least the first six months.

Hot weather, and what not to reach for

In a heatwave the answer is subtraction. Strip back to a nappy and a vest, or a nappy alone in a genuinely hot room, with a 0.5 tog bag or nothing at all over her. Close the curtains on the sunny side through the day, open the house up in the evening once the outside air is cooler, and aim any fan at a wall rather than at the baby.

Offer extra feeds. A baby under six months gets her fluid from milk rather than from water, and hot days usually mean more frequent, shorter feeds rather than a change in anything else. Expect worse naps and a later, more broken settle for as long as the weather lasts. That is the room, not a change in her sleep, and it goes back to normal when the temperature does.

The things never to use around a sleeping baby are worth naming: no hot water bottle, no electric blanket, no cot pushed against a radiator, no heater or fire aimed at her, and no cot standing in direct sunlight. Every one of those heats a baby who cannot move away from it or tell you.

When the room is too cold

Cold happens far less often than overheating in a heated house, and it is the easier of the two to fix. Below about 16C, add a layer under the bag rather than something over the top: a long-sleeved bodysuit, or a sleepsuit with feet, and then the 2.5 tog bag on top of it.

What you are avoiding is loose bedding creeping back into the cot because the room is chilly. A pile of blankets is not the answer to a cold room; a warmer vest under a well-fitting bag is. And if she wakes at four every morning and you have decided the room is to blame, check it before you rebuild the night — a cheap thermometer settles the argument, and the early morning waking guide covers the several other reasons that hour goes wrong.

Keeping track, and telling somebody else

If you cannot tell whether the temperature is the problem, write down the room reading, what she wore and how the night went for a week. Three or four nights of that beats a fortnight of guessing, and a printed night sheet is easier to fill in at 2am than a phone is. Look for the pattern rather than the single bad night.

The other person who needs this is whoever puts her down when you are out. What she wears, which bag, what the room should read, and the fact that hands do not count all belong on paper rather than in a text message — the babysitter information sheet has a line for each of them, alongside the numbers a sitter would otherwise have to hunt for. Bags and layers also travel badly, which is why the travel guide puts room temperature at the top of the list of things that are wrong in an unfamiliar house.

When it is not a temperature problem

Room temperature explains a certain amount and no more. A baby who feels hot to the touch may have a temperature rather than too many layers, and that is a different page and a different threshold — the guide to sleep during illness carries the fever numbers and the signs that mean a phone call today. Get medical help straight away for a baby who is very hard to rouse, whose breathing is fast or laboured, who is pale or mottled, or who has a rash that does not fade when pressed. And if she cannot be settled at all, is feeding poorly or not gaining weight, that is a conversation with your pediatrician or health visitor. This page is general information, not medical advice, and it cannot see your baby.