how to keep baby warm at night

How to Keep a Baby Warm at Night (Evidence-Based Guide)

Oct 29, 2020

How to Keep a Baby Warm at Night (Evidence-Based Guide)

A complete guide to safely keeping your baby warm at night without blankets

Baby, it’s cold outside…

…but is it cold inside?

The very first thing to know about keeping your baby warm at night is that you should dress him for sleep based on the temperature of the room, not the temperature outside.

I’m going to give you a great chart for this in just a moment!

The second thing to know is how to check if your baby is warm or cold. Certain parts of the body might feel cold, but this can be deceiving!

Get ready for some simple, evidence-based tips for keeping your baby warm at night in a cold house, while insuring that he doesn’t overheat. 

Thankfully, babies have no idea ‘tis the season for cozy blankets and hot cocoa.

cold weather blanket hot chocolate

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keep baby warm sleep night pin

How to dress your baby for sleep in a cold house

It can be hard to know what your baby should wear under a swaddle or sleep sack.

There are 3 simple methods to determine how warmly to dress your baby for sleep:

1) The AAP’s “1 layer more” guideline

2) Layering based on the temperature of the room

3) Adjusting based on your baby’s core temperature

I’m about to cover each of these methods in depth, but keep in mind that none of these are hard and fast rules. They tend to work best when used in conjunction.

1AAP guidelines for dressing your baby for bedtime

Here is the American Academy of Pediatrics‘ rule of thumb:

“In general, infants should be dressed appropriately for the environment, with no greater than 1 layer more than an adult would wear to be comfortable in that environment.”

But beware, if you’re a frileuse like me and you wear a down jacket in the house, take this guideline with a grain of salt. You don’t want your baby overheating.


2Layering baby’s sleepwear based on the temperature of the room

Parents commonly ask, “how many layers should baby wear overnight?” and “how do you keep a baby warm at night in the winter?”

No matter the season, what matters most when dressing your baby for sleep is the temperature of the room he’ll be sleeping in.

One of the best ways to determine whether your baby is dressed warmly enough (or too warmly) for sleep is to get an accurate indoor thermometer and then go by this chart…

infographic dress baby for sleep

I’m going to explain everything in this infographic in a moment. If you’d rather skip ahead, use these links:

What is TOG |  The ABCs of safe sleep | Why no hats? | Why no mittens?When and why to stop swaddling

So, for example, if you’re wondering how to dress a baby for sleep in a 70 degree room, you’d look at the chart and see that you should layer the following:

1.0 TOG sleep sack + pajamas with long sleeves and pants + short sleeve onesie

(I’ve linked some of my favorites to check out!)

Now for the third way to determine how warmly to dress your baby for sleep:

3Checking your baby’s core temperature

All guidelines aside, every baby is different. It’s important to check your own baby to make sure he is neither too hot or too cold.

The best way to do this is to feel his core. His back or chest should be warm, but not hot, and certainly not sweaty. You’ll want to add or remove layers accordingly.

check baby's core temperature

It may take some trial and error to determine which combination of sleepwear works best for keeping your baby comfortably warm at night.

Note: Don’t worry about your baby’s head or extremities being cold as these are poor indications of his actual temperature. (Babies have poor circulation).

The best infant sleepwear for layering

Before we get into the safety questions about swaddling, hats, and mittens, let’s quickly talk about what your baby should wear to sleep!

Whether you have an unheated house in the cooler months, or an air-conditioned house in the warmer months, here’s what you’ll want to have handy for layering:

  • Sleep sacks of different thicknesses
  • Long sleeve pajamas (sleeper/footie or 2-piece set)
  • Long sleeve onesies
  • Short sleeve onesies
  • Socks

Here are a few of my favorites!

My favorite sleep sack of all time! Cozy and hilarious. Other styles too! Sizing starts at ‘birth’ (23 inches, 10 lbs). Don’t use the hat for sleep.
sleep sack to keep baby warm
Comfortable, stretchy, and trendy pajama set! Sizing starts at 6-12 months.

neutral 2-piece baby pajamas

Simple, cute, and reasonably priced short sleeved onesie! Sizing starts at newborn.

gray onesie

This brand makes high quality, affordable, GOTS certified organic cotton baby clothes. Sizing starts at newborn.

baby sleeper footie pajamas

Long sleeve sleep sacks are great for keeping your baby warm at night, especially when he’s wearing short sleeves! We loved this fleece one SO much. Sizing starts at 0-3M.

long sleeved sleep sack for warmth

Is it safe to use a swaddle blanket to keep your baby warm?

Swaddling is a great way to keep a newborn warm and cozy; however, it’s not safe for babies past a certain age and developmental stage.

According to the AAP,

“Parents should stop swaddling as soon as their baby shows any signs of trying to roll over. Many babies start working on rolling at around 2 months of age.”

it's no longer safe to swaddle when baby shows signs of rolling

Many safe sleep experts err on the side of caution, directing parents to stop swaddling at 8 weeks or first signs of rolling, whichever comes first.


Because if a swaddled infant rolls onto his stomach, the risk of death is high.

(Read more about what to do when your baby starts rolling here).

That leads us to sleep sacks…

How to keep a baby warm at night without swaddling

New parents often ask, “what should I cover my baby with at night to keep him warm in his crib or bassinet?”

Once it’s no longer safe to swaddle, the best way to keep your baby warm at night (and during daytime naps too!) is to use a sleep sack.

Get our favorite avocado sleep sack here!

A sleep sack is a wearable blanket that’s safe for all ages and stages, including newborns and toddlers. Adults too!

Check out my evidence based overview of Safe Sleep 101!

Here are the answers to frequently asked questions about sleep sacks:

Is baby warm enough in a sleep sack?

Three things will determine whether your baby is warm enough in a sleep sack:

1 – The TOG rating of the sleep sack.

2 – The other layers your baby is wearing.

3 – The temperature of the room.

It’s absolutely possible for your baby to be warm enough in a sleep sack, even in a cold room! Sleep sacks are great for safely keeping your baby warm in his crib or bassinet.

What are TOG ratings?

Thermal Overall Grade (TOG) is the standard of measure for how much heat a garment retains.

You can find out the TOG rating of a sleep sack by:

  • Checking the tags
  • Visiting the company’s website
  • Contacting the manufacturer

The higher the number, the warmer the sleep sack.

Here’s an overview of the different TOGs, along with sleep sack recommendations for each respective TOG…

TOG 0.5

The lightest sleep sacks are great for comfort (and sticking to a bedtime routine) when baby’s room is around 70 degrees or higher. Here’s a great option from a trusted brand.

TOG 1.0

In my opinion, this is the most versatile weight. I like the microfleece sleep sacks because they’re cozy without being too thick. This is a great choice that we own and love.

TOG 1.5

Slightly warmer than the previous, here’s a great ‘plush dot’ sleep sack made from soft minky.

TOG 2.0

If the temperature in baby’s room is 63 degrees or below, you’ll probably want a warm sleep sack. Most brands skip the 2.0 TOG (not sure why) and sell the 2.5 instead…

TOG 2.5

This is typically the warmest indoor option. If your baby’s room is extra chilly and/or you don’t plan on layering, here’s a top rated extra warm sleep sack.

TIP: If you’re not inclined to buy multiple types of sleep sacks, get an all-season one…

What is the best all-season sleep sack?

There’s a splurge option that’s absolutely worth considering.

And actually, when you price out what you’d be spending on multiple kinds of sleep sacks in different sizes, it’s not as expensive as it appears!all season sleep sack keep baby warmFirst of all, this sleep sack will last you 2 years! This sounds crazy, but yes, it really will fit your 2 month old and your 2 year old.

In order to understand the major appeal of this cult-favorite product, though, you need to understand the properties of merino wool.

Merino wool is this weird unicorn of a fabric that can keep you warm OR cool. Think of it like styrofoam that maintains the temperature of a warm or cold drink.

That’s why it works for “all seasons.”

Don’t let the $100-ish price point scare you away…

  • This is a HIGH QUALITY product that will hold up over time.
  • It will fit for 2 years. You won’t have to regularly size up like you’ll need to for other sleep sacks.
  • It will keep your baby comfortable year-round.

Order one with fast free shipping!

When can you safely give your baby a blanket for sleep?

Many parents and caregivers often inquire, “when can I cover baby with a blanket?”

Blankets in the sleep space are unsafe for babies until they are at least 12 months old, as loose bedding significantly increases the risk of sleep-related death.

After your baby turns 1, check your crib’s user manual to see whether blankets may be used. 

Note: No blankets means no blankets ANYWHERE! Even *under* your baby. The only items in the sleep space should be a standard mattress pad (optional) and a fitted sheet.

How to keep your baby’s hands and feet warm at night

Before we talk about mittens and socks, it’s important to reiterate that cold hands and feet aren’t a good way to gauge an infant’s temperature.

The AAP explains,

Bluish and cool hands and feet are normal on healthy infants, and the cool sensation of extremities likely do not bother baby at all. -Natasha Burgert, MD, FAAP

As long as your baby is dressed in appropriate layers and his core is warm, you don’t need to worry about cold hands and feet.

Are mittens safe for infant sleep?

Parents commonly ask, “my baby’s hands are ice cold at night, should he wear mittens?”

Mittens aren’t recommended for infant sleep because babies need their hands to explore and self-soothe.

If you still decide to cover your baby’s hands, don’t use mittens, as they could pose a suffocation risk. Instead, get a sleeper with mitten cuffs like this one.

What about socks?

Many parents want to know, “should babies wear socks to bed?” and “should babies wear socks under sleepers?”

If your baby’s room drops below ~64 degrees, it’s a good idea to make sure his feet are covered.

Unless it’s really chilly in your baby’s room (i.e. the heat is broken during the winter), it’s probably unnecessary to layer socks underneath footie pajamas (sleepers), but use your own discretion.

Socks are generally safe for sleep if your baby is wearing a sleep sack or swaddle (which covers the lower portion of his body).

However, if your baby tends to pull his socks off and you’re concerned about them posing a suffocation hazard, footie pajamas are your best bet.

baby bodysuit sleeper footies

How to keep baby’s head warm at night

As long as your baby’s core is warm (but not hot and sweaty), don’t worry about his ears, nose, and cheeks feeling cold. Babies have poor circulation so this is normal.

Hats aren’t safe for sleep as they present risks of suffocation and overheating.

newborn baby wearing hat in hospital

Hats are used in the hospital for brand new babies but should not be used for sleep once you’re home.

How to keep your baby from overheating during sleep

Parents commonly ask, “how do I know if my baby is too hot while sleeping?”

Many caregivers also want to know if it’s safe for babies to be sweating while sleeping.

Overheating is a risk factor for SIDS/SUID so this is something to take extremely seriously.

    Here are 7 tips for making sure your baby doesn’t get too hot:

    • Don’t put baby to sleep with a hat or hood. Infants need to be able to release excess heat through their heads. (Hats and hoods are also suffocation risks).
    • Keep an eye on the temperature of baby’s room if you turn up the heat in the house. (Buy an accurate thermometer to keep in there!)
    • Pay attention to signs of overheating, which may (or may not) include a red face, rapid breathing, and sweating. Check to make sure baby’s core isn’t hot. If your baby is sweating in his sleep, it’s a sign that he’s probably dressed too warmly.
    • Avoid putting baby to sleep in thick sweaters or other materials best suited for outdoors.
    • Don’t dress baby in more than 1 additional layer than you’re comfortably wearing. Be sure not to over-bundle.
    • Use the infographic at the beginning of this article as a guide for how to appropriately layer baby’s clothes based on the temperature of the room.
    • When in doubt, dress baby in fewer layers rather than more layers. It’s better for an infant to be slightly too cold than too warm.

    How to tell if your baby is cold at night

    Generally, you won’t have to worry about your baby getting cold during sleep as long as he’s dressed appropriately based on the temperature of the room.

    Your baby will wake from sleep and cry if he gets too cold. If his core feels cool, consider adding a layer.

    baby dressed in warm outfit

    How to keep baby’s room warm at night

    If you don’t have central heating—or you do, but your house heats unevenly, you might be wondering, “how do I keep baby warm without a heater” and “what do I do when baby’s room gets cold at night?”

    It may make you feel better to know that there is no officially recommended room temperature for infant sleep.

    While many experts suggest an approximate range of 68-72 degrees, if your baby’s room is cooler than this, there’s no cause for concern as long as he is dressed appropriately and his core feels warm.


    Here are 4 tips for safely warming up a nursery if you don’t have a central heating system:

    handdrawn starTurn on a space heater in your baby’s room before bedtime.

    Be sure to turn it off as soon as you leave the room or go to sleep. (More on space heaters in the next section!)

    handdrawn starUse a heating pad or hot water bottle to warm your baby’s sheets before placing him in his crib or bassinet.

    Touch the surface to make sure the surface isn’t too hot before you put him down.

    And of course, be sure to remove these objects from the crib!

    handdrawn starPay attention to the windows:

    • Move baby’s crib or bassinet away from windows.
    • Caulk or weatherstrip tiny gaps in the windows that are letting in cold air.
    • Make sure the curtains are closed.
    • Add thick curtain liners.

    handdrawn starIf you have a ceiling fan, switch its rotation to clockwise to push warmer air down from the ceiling.

    Is it safe to use a space heater in baby’s nursery?

    This is a common question from parents looking to keep their babies warm at night in winter.

    The answer is that space heaters are major fire hazards.

    There is no such thing as a safe space heater for a baby’s room that can be left unattended.

    Not to mention, even the most advanced models can malfunction and make your baby’s room too hot, which is a SIDS risk.

    Even with all the new safety features such as timers and adjustable thermostats, there are plenty of gut-wrenching horror stories from ‘loss parents’ whose space heaters malfunctioned while their babies were unattended.

    space heater in baby's room

    If you’d like to warm up the nursery, it’s best to turn the space heater on before bedtime while you’re in the room (and awake!); and then turn it off when you put your little one down to sleep.

    The CPSC provides several critical guidelines for the use of space heaters. I’ll quickly call your attention to three of them:

    • Never leave the heater on while unattended, or while sleeping.
    • Do not use extension cords or power strips with space heaters.
    • Make sure the heater is AT LEAST 3 feet away (in all directions) from curtains, furniture, toys, and any objects.

    What about fan heaters?

    The same CPSC safety guidelines apply to the popular (and expensive) Dyson Hot+Cool, which is an air purifier that also acts as a heater.

    The user manual calls for “extreme caution” around children and when left unattended. The manual also warns of flammability and burns from hot parts.

    Following the ABCs of safe sleep

    Any conversation about keeping your baby warm at night would be incomplete without addressing the #1 cause of infant death, SIDS/SUID.

    To keep your baby safe while he sleeps, always follow the ABCs.

    A – Alone – no people, blankets, or objects in the sleep space
    B – Back – baby should be put down to sleep on his back, never on his belly or side
    C – Crib – a regulated crib, bassinet, or play yard

    Read this detailed evidence-based article about the ABCs of safe sleep.

    the abcs of safe sleep alone back crib prevent sids

    Final thoughts on safely keeping your baby warm at night without blankets

    The keys to keeping your baby safely warm and cozy are to layer appropriately (without over-bundling) and to feel your baby’s core to ensure he is warm but not hot.

    Do not be alarmed by your baby’s cold hands and feet. Not only is this normal, but it’s a poor indication of your baby’s temperature.

    Be sure to avoid blankets and any loose bedding for infants under 12 months of age.

    How to keep your baby warm at night

    How to Keep a Baby Warm at Night (Evidence-Based Guide)How to Keep a Baby Warm at Night (Evidence-Based Guide)