Key highlights
- Cool hands and feet are normal — check the chest instead.
- Aim for a room between 16–20°C (61–68°F).
- Add layers underneath the sleep sack, never blankets on top.
- Never use a hat indoors, even if the room feels cold.
- Warm the room, not the cot — no heaters, hot water bottles or electric blankets.
Parents worry about the cold far more often than the numbers suggest they need to. The NHS, The Lullaby Trust, NCT and Red Nose Australia all agree that a slightly cool room is safer than a warm one — but if the room drops well below 16°C, or your baby has kicked off their sleep sack, it's worth knowing how to check and what to do.
How to check properly
Slide two fingers inside your baby's sleep sack and feel their chest, tummy or the back of the neck. Warm and dry is exactly right. Cool hands and feet are normal — babies naturally have poorer circulation to their extremities, and cold fingers alone don't mean your baby is cold.
Signs your baby may actually be too cold
- A cool or cold chest or back, not just cool hands
- Pale or mottled skin across the torso
- Difficulty settling, restlessness or frequent night waking
- Shivering (rare in babies — treat as an important warning sign)
- Feeding well but not gaining weight in a persistently cold room
How to safely add warmth
The safest way to warm a baby is to add a thin extra layer underneath the sleep sack — for example, adding a long-sleeved vest and sleepsuit under a 2.5 TOG sack instead of just a sleepsuit. The Lullaby Trust and NCT both warn against piling blankets on top of a sleeping baby, as loose bedding is a known SIDS risk.
If the whole room is genuinely too cold, warm the room, not the cot. A thermostatically controlled heater on low, well away from the cot and any bedding, is far safer than an electric blanket, a hot water bottle, or a heater aimed directly at your baby — all of which are explicitly advised against by Red Nose Australia and The Lullaby Trust.
Quick rule of thumb
One thin layer under a suitable TOG sleep sack keeps most babies comfortable down to about 16°C. Below that, add a second thin layer underneath — never a blanket on top.
What to avoid
- Loose blankets, duvets, quilts or cot bumpers
- Hats or hooded sleepwear for sleep indoors
- Hot water bottles, wheat bags and electric blankets
- Sleeping your baby in a coat or snowsuit indoors or in the car
A calm, cool nursery with the right TOG and one or two thin layers underneath is what all four major safer sleep organisations recommend — and it's almost always all your baby needs to stay comfortable through the night.