By Angelica Videla — Certified Baby and Toddler Sleep Consultant, London | Supporting families across the UK, Europe, US, and Australia
Quick Answer
Dress your baby based on the actual room temperature, not the season. At 18 to 20°C (the most common UK nursery temperature), a 2.5 TOG sleeping bag with a short-sleeve bodysuit is typically right. At 20 to 22°C, switch to 1.0 TOG with a long-sleeve bodysuit. Above 24°C, use 0.5 TOG with just a nappy or vest. Check the back of the neck — not hands or feet — to assess temperature.
Why getting this right matters for sleep
Temperature is one of the most common and most easily fixed causes of disrupted baby sleep. A baby who is too warm sleeps more lightly and wakes more frequently. A baby who is too cold wakes earlier in the morning as body temperature naturally dips in the pre-dawn hours.
In my experience working with families, adjusting clothing and TOG for the actual room temperature reduces unnecessary night waking in roughly one in three cases where temperature was a contributing factor. It is the first thing I check with every family.
Dressing guide by room temperature
Below 16°C (very cold room)
3.5 TOG sleeping bag + long-sleeve bodysuit + pyjamas or sleepsuit. Consider socks. This temperature is unusual in UK homes with central heating but can occur in older properties or during heating failures.
16 to 18°C
2.5 TOG sleeping bag + long-sleeve bodysuit. This is a common temperature in UK homes during winter with central heating that switches off at night.
18 to 20°C (ideal range)
2.5 TOG sleeping bag + short-sleeve bodysuit. This is the most common combination for UK families. The room is within the ideal sleep temperature range and the 2.5 TOG with a light layer underneath maintains optimal warmth.
20 to 22°C
1.0 TOG sleeping bag + long-sleeve bodysuit. Switch to the lighter sleeping bag at this temperature. A 2.5 TOG in a room above 20°C is the most common cause of overheating I see in the families I work with.
22 to 24°C
1.0 TOG sleeping bag + short-sleeve bodysuit or vest.
24 to 27°C (warm room — summer)
0.5 TOG sleeping bag + nappy only, or a short-sleeve bodysuit without a sleeping bag. In a UK heatwave, this is the most common scenario.
Above 27°C (very warm)
Nappy only. No sleeping bag. Consider a muslin wrap if your baby prefers the comfort of being covered.
How to check if your baby is the right temperature
Touch the back of the neck or chest. Warm and dry means the temperature is right. Hot or sweaty means too warm. Cool or cold means too cold.
Ignore hands and feet. Babies naturally have cooler extremities due to their immature circulatory system. Cold hands are normal and do not indicate that your baby is cold.
Watch for signs of overheating: sweaty neck or back, damp hair, flushed face, restless sleep, frequent unexplained waking.
Watch for signs of being too cold: cool chest or tummy, mottled skin, unusually early waking (before 5:30am).
Common dressing mistakes
- Adding a blanket on top of a sleeping bag — unsafe under 12 months and causes overheating at any age
- Using fleece sleepsuits inside a sleeping bag — fleece traps heat and does not breathe well
- Dressing for the season rather than the actual room temperature
- Adding layers because the baby’s hands feel cold — cold hands are normal
- Using the same TOG sleeping bag year-round without checking room temperature
- Overdressing a baby who is unwell — fever raises body temperature and additional layers can cause dangerous overheating
What fabric is best for baby sleepwear?
Cotton. Breathable, widely available, and easy to wash. The most practical choice for everyday sleepwear.
Bamboo. Softer than cotton and naturally temperature-regulating. Excellent for babies with sensitive skin. Slightly more expensive.
Merino wool. The best natural temperature regulator — keeps warm in cold and cool in heat. More expensive but useful for travel or homes with significant temperature variation.
Avoid polyester and synthetic fabrics. These trap heat and do not breathe, increasing the risk of overheating.
For sleeping bag recommendations, see our guide: best sleep sacks for babies. For room temperature monitoring: best nursery thermometers.
Frequently Asked Questions
How should I dress my baby for sleep at 20 degrees?
A 1.0 TOG sleeping bag with a long-sleeve bodysuit underneath. At 20°C, a 2.5 TOG is too warm for most babies.
What should a baby wear to bed in summer?
In rooms above 24°C, a 0.5 TOG sleeping bag with a nappy or short-sleeve vest. Above 27°C, a nappy alone may be sufficient.
Should a baby wear socks to bed?
Only in rooms below 16°C. In most UK homes with central heating, socks are unnecessary and can cause overheating when combined with a sleeping bag.
My baby’s hands are always cold at night — should I add layers?
No. Babies naturally have cooler hands and feet. Check the back of the neck — if it is warm and dry, your baby is the right temperature.
Can overdressing cause night waking?
Yes — overheating is one of the most common and easily fixable causes of frequent night waking.