A light sleep bag is a thin, sleeveless sleep bag for hot nights. It zips on over your baby's bedtime clothes and takes the place of a sheet or blanket, so nothing loose lies in the crib. In the US, sleep bags are called sleep sacks.
TOG is the warmth number on a sleep bag's label. The usual weights are 0.5, 1.0 and 2.5, and the higher the number, the warmer the bag. A 0.5 TOG bag is the lightest: thin fabric, without the padding of a winter bag.
A 0.5 TOG bag is for a room of 24–27°C (75–81°F) at night. It suits a summer heatwave, an upstairs room that holds the day's heat, or a holiday somewhere hot.
- For ages0–3years
- You'll need2–3per size
- For a room at24–27°C75–81°F
Does your baby need one in summer?
No. In really hot weather, a short-sleeve bodysuit or even just a diaper is fine on its own.
A light bag helps if your baby is used to a sleep bag and settles better in one. You can keep the same bedtime routine all summer.
It also helps when the room cools down toward morning, as it can with air conditioning or an open window. The bag keeps a thin cover on your baby, and unlike a sheet, it cannot be kicked off or pulled over the face.
What light sleep bags are made of
For warmth, go by the TOG number, not the fabric: the number already takes the fabric into account. Then choose by how it feels.
Cotton muslin
Cotton woven loosely, like gauze, often in two layers. It is light and airy, with a soft, crinkled look, but it does not stretch.
Cotton jersey
The smooth, stretchy knit of a T-shirt. It feels like a bodysuit and gives a little when your baby kicks.
Bamboo
A silky, stretchy knit. Shops call it bamboo, but the label says rayon or viscose made from bamboo.
How to choose a light sleep bag
1. The TOG rating
You cannot judge TOG by sight: a 0.5 and a 1.0 TOG bag can look the same. Read the label, and follow the maker's room chart, even where it differs from the usual ranges.
- Good: 0.5 TOG on the label
- Good: A room chart from the maker
- Not good: No TOG anywhere
2. Sleeveless, with close armholes
Bare arms let heat out, which is what you want on a hot night. The armholes should sit close without pinching, so your baby's arms cannot slip back inside.
- Good: No sleeves
- Good: Armholes close, not tight
- Not good: Armholes that gape
3. The size for your baby's weight
Most sleep bags are fitted by weight, not age, so check your baby's weight on the size chart. If a bag is too big, its neckline can slide up over the chin.
- Good: Your baby's weight in the size range
- Good: Neckline below the chin
- Not good: A size up, to grow into
What to put on underneath
A short-sleeve bodysuit. The bag covers the body and legs, and the arms stay bare.
If your baby still feels hot, take the bodysuit off and use the bag over just a diaper. How to dress a baby for sleep has an outfit for every room.
Which TOG bag to choose for tonight
Your room tonight
25°C (77°F)
Move the thermometer to your room's temperature.
Short-sleeve bodysuit, 0.5 TOG Light sleep bag
Short-sleeve bodysuit
0.5 TOGLight sleep bag
Makers' charts differ, so follow your bag's label.
Questions parents ask
When is it too hot for a sleep sack?
At 28°C (82°F) and warmer. Leave the bag off and put your baby down in just a diaper. You do not need a thinner 0.2 TOG bag for these nights.
Can a baby overheat in a sleep sack?
Yes, if the bag and the clothes under it are too warm for the room. Feel the chest or the back of the neck, not the hands, and if the skin is hot or sweaty, take off a layer.
What's the difference between 0.5 and 1.0 TOG?
A 1.0 TOG bag is warmer, for a room of 20–24°C (68–75°F). If the light bag is all you have on a cooler night, a footed sleepsuit under it works down to 20°C (68°F). In a colder room, change to a warmer bag.
Can a newborn sleep in a 0.5 TOG sleep sack?
Yes, once your baby is heavy enough for the smallest size: check the minimum weight on the label. Until then, a short-sleeve bodysuit on its own is fine on a hot night.
Is there a 0.5 TOG swaddle?
Yes, light swaddles are sold for warm nights. Swaddling stops once your baby starts trying to roll, because a rolling baby needs free arms, and a sleep bag comes next.
Do they make 0.5 TOG sleep sacks for toddlers?
Yes. Light sleep bags come in toddler sizes, up to 2 to 4 years with some makers, and some have legs for a child who walks.
