The TinyLayers Guide
What Should My Baby Wear to Sleep Tonight?
Quick answer
It's 9pm, the nursery reads 21 degrees, and you're standing over the drawer holding two sleep sacks and a bodysuit, doing mental math you were never taught. Every parent knows this moment. The good news: the answer follows a simple rule, and you can verify it in ten seconds once your baby settles.
The room decides, not the calendar
Babies sleep in a room, not in the weather forecast. A July nursery with air conditioning can be colder than a January one with radiators. So the only number that matters is the temperature near the crib - a small thermometer there beats any seasonal rule. Once you know the room, sleepwear follows.
A plain-English chart
Sleep sack warmth is measured in TOG (Thermal Overall Grade) - higher is warmer. This table reflects common TOG chart guidance used by major sleepwear brands; treat it as a starting point, not a prescription, and check your brand's own chart.
| Room temperature | Typical outfit |
|---|---|
| Under 16°C (61°F) | 2.5 TOG sack + sleepsuit + long-sleeve bodysuit |
| 16-19°C (61-66°F) | 2.5 TOG sack + long-sleeve bodysuit |
| 20-21°C (68-70°F) | 1.0 TOG sack + long-sleeve bodysuit |
| 22-23°C (72-73°F) | 1.0 TOG sack + short-sleeve bodysuit |
| 24-25°C (75-77°F) | 0.5 TOG sack + short-sleeve bodysuit |
| 26°C+ (79°F+) | 0.5 TOG or lighter, or bodysuit only |
Notice what's missing: blankets. The American Academy of Pediatrics recommends keeping loose blankets, pillows, and soft objects out of the sleep space entirely for the first year - a wearable sleep sack does the blanket's job without the risk.
The chest check: your ten-second confirmation
Charts get you close; your baby tells you the rest. About 10-15 minutes after settling, slide a hand onto your baby's chest or the back of the neck:
- Warm and dry - you got it right. Close the door calm.
- Sweaty, damp, or hot - remove a layer.
- Chest feels cool - add a layer.
Cool hands and feet are normal in sleeping babies and not a sign to bundle up - immature circulation keeps extremities cooler. The chest is the honest reading.
Three rules that don't change with temperature
- No hats indoors during sleep. Babies shed heat through their heads; a hat blocks that and raises overheating risk.
- Stop swaddling at the first sign of rolling, per AAP guidance - usually around 2-3 months. Move to an arms-free sack.
- When torn between two options, go lighter. Overheating is linked to sleep-related infant death risk; slightly cool is the safer miss, and the chest check will catch it either way.
Related guides
- What's the best room temperature for a sleeping baby?
- Is my baby too hot or too cold? How to actually tell
Sources
TinyLayers provides general dressing guidance only and does not replace medical advice. Every baby is different - for fever, premature birth, or any medical concern, follow your clinician's guidance.
Frequently asked questions
Should my baby wear a hat to sleep?
No. Babies release heat through their heads, and safe-sleep guidance from the AAP and NHS says no hats indoors during sleep. Hats are for outdoors in the cold.
Does my baby need socks at night?
Usually not. A footed sleepsuit or a sleep sack covers the feet, and cool hands and feet are normal in sleeping babies. Judge warmth by the chest or back of the neck, not the toes.
When should we stop swaddling?
At the first signs of rolling, per AAP safe-sleep guidance. Many babies show rolling attempts around 2 to 3 months. After swaddling, an arms-free sleep sack is the usual next step.
What TOG sleep sack should I use?
As a common rule of thumb: around 2.5 TOG for rooms of 16-19°C, 1.0 TOG for 20-23°C, and 0.5 TOG or lighter above 24°C - adjusting the bodysuit underneath. Brands differ, so check their chart and always confirm with the chest check.