How to Dress Your Baby for Sleep Safely

Working out what your baby should wear to sleep can feel surprisingly stressful, especially in the early weeks. The good news is that all of the major safer sleep organisations — the NHS, The Lullaby Trust, NCT and Red Nose Australia — broadly agree on what safe, comfortable sleepwear looks like. Once you know the framework, the daily decision becomes a lot easier.

Start with the room, not the outfit

The single most useful thing you can do is measure the temperature of the room your baby actually sleeps in, using a simple nursery thermometer. The Lullaby Trust and NHS recommend a room temperature between 16°C and 20°C (61–68°F), which is often cooler than adults find comfortable. Red Nose Australia gives similar guidance, suggesting a room that feels comfortable for a lightly dressed adult.

Rooms upstairs, rooms in the roof, and rooms that face the afternoon sun can be several degrees warmer than the rest of the house. In hot weather, cooling the room — closing blinds during the day, opening windows in the evening, or using a fan aimed away from the cot — is almost always safer than dressing your baby in less than a light layer.

Choose a TOG, then layer underneath

A sleep sack (also called a sleeping bag) is widely recommended by The Lullaby Trust and NCT as a safer alternative to loose blankets, because it can't ride up over your baby's face. Sleep sacks are rated by TOG, a measure of thermal insulation. As a rough starting point:

• 2.5 TOG for cooler rooms around 16–20°C (61–68°F)
• 1.0 TOG for warmer rooms around 22–24°C (72–75°F)
• 0.5 TOG for hot rooms above 24°C (75°F)

Once you've picked the TOG, add or remove layers underneath. In a typical 18°C nursery, a long-sleeved vest and a sleepsuit under a 2.5 TOG sack works for many babies. In a warm 24°C room, a short-sleeved vest under a 1.0 TOG sack is usually plenty. Above 27°C, most manufacturers and The Lullaby Trust suggest a nappy and a light vest only, with no sleep sack.

How to check if your baby is the right temperature

Hands and feet are a poor guide — they're often cool even when the rest of your baby is perfectly warm. The NHS and NCT both recommend feeling your baby's chest, tummy or the back of the neck. It should feel warm and dry, not hot, sweaty or clammy. Damp hair, a flushed face, rapid breathing or restlessness can all be signs of overheating, which is linked to an increased risk of SIDS.

If your baby feels too warm, remove a layer. If they feel cold on the chest, add a thin extra layer underneath the sleep sack rather than piling a blanket on top.

Safer sleep essentials

• Always place your baby on their back to sleep, for every sleep.
• Use a firm, flat, waterproof mattress with a well-fitting sheet.
• Keep the cot clear of pillows, duvets, cot bumpers, pods and soft toys.
• Never cover your baby's head or face, and don't use hats indoors.
• Avoid loose blankets — a correctly sized sleep sack is safer.
• Keep the room smoke-free, day and night.

What about out and about, or in the car?

The Lullaby Trust and Red Nose both warn against leaving babies in thick coats, snowsuits or padded car-seat inserts while asleep in a car seat, as these can cause rapid overheating and interfere with the harness fit. Dress your baby in thinner layers for travel and add a blanket over the top of the harness that can be removed once you're somewhere warm.

At home, the goal is the same every night: a cool room, a suitable TOG, sensible layers, and a clear, flat sleep space. Once you've done it a few times, it stops feeling like a decision and starts feeling like a routine — which is exactly what safer sleep guidance is designed to give you.