Safe Sleep Guide UK 2026 NHS and Lullaby Trust Guidance Explained
Everything parents need to know about safe sleep — the rules, the reasons behind them, the risks, and how to set up a sleep environment that follows current NHS and Lullaby Trust guidance.
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Sudden Infant Death Syndrome (SIDS) — sometimes called cot death — is the sudden and unexplained death of a baby who appears to be healthy. In the UK, around 200 babies die from SIDS each year. The cause is not fully understood, but research over the past 30 years has identified a number of factors that significantly increase and reduce the risk. The guidance in this article reflects the current NHS and Lullaby Trust recommendations as of 2026. If guidance changes, the Lullaby Trust website at lullabytrust.org.uk carries the most current version.
① The Safe Sleep Rules
The NHS and Lullaby Trust provide a clear set of safe sleep recommendations. These are not advisory preferences — each recommendation is supported by evidence showing it meaningfully reduces SIDS risk. The most effective way to protect your baby is to follow all of them consistently.
② Setting Up the Sleep Environment
The cot or crib
Your baby’s sleep space should be a dedicated cot, crib, bedside crib, or Moses basket — not a bouncer, car seat, swing or any other semi-reclined surface. The sleep surface must be firm and flat. A bedside crib is ideal for the first six months — it keeps baby in the room, makes night feeding easier, and maintains a safe separate sleep space. See our best bedside cribs guide for recommendations. When moving to a full cot at around six months, see our best cots guide.
The mattress
Always buy a new mattress — even when the cot frame is second-hand. The NHS and Lullaby Trust advise against second-hand mattresses because bacteria and mould can persist inside foam even after cleaning and have been associated with increased SIDS risk. The mattress must be firm — when pressed, it should spring back immediately rather than conforming to the shape of your hand. Memory foam mattresses are not suitable. See our second-hand baby gear guide for what is and is not safe to buy used.
Bedding
The safest bedding is no bedding. A baby sleeping bag in the correct tog for the season keeps the baby warm without any loose fabric. If using sheets and blankets, use lightweight cellular blankets (not duvets or quilts), tuck them firmly under the mattress, and place the baby at the foot of the cot so they cannot wriggle under the covers. Remove all pillows, bumpers, nests, and positioners from the sleep space.
③ Sleep Position — Back Sleeping
Always place your baby on their back to sleep — for every sleep, day and night, until they can roll both ways independently. This is the most evidence-backed safe sleep recommendation and alone accounts for most of the 80 percent reduction in SIDS rates seen since the 1990s.
What if my baby rolls onto their front?
Once a baby can roll from back to front and front to back independently — typically from around 5–6 months — you do not need to reposition them if they roll during sleep. Continue placing them on their back to start every sleep. Before this milestone, if you find your baby has rolled during sleep, gently reposition them onto their back.
What about tummy time?
Tummy time — placing a baby on their front while awake and supervised — is important for development and does not conflict with back sleeping for sleep. Tummy time strengthens neck and shoulder muscles. It should always be supervised. The rule is simple: front for play, back for sleep.
What if my baby seems to prefer sleeping on their front?
Some babies settle more easily on their front. The evidence on SIDS risk is clear enough that the NHS guidance is firm: back sleeping for all sleep until independent rolling. If you have specific medical concerns about your baby’s sleep position — for example, if they have reflux — speak to your GP or health visitor. Do not change your baby’s sleep position without medical advice.
④ Room Temperature and Layering
The recommended room temperature for a baby’s sleep space is 16–20°C. Overheating is a significant risk factor for SIDS. A room thermometer is one of the most useful items in a nursery — it removes guesswork from temperature decisions and lets you respond to seasonal changes accurately.
Choosing the right sleeping bag tog
Baby sleeping bags are rated by tog — the standard measure of thermal insulation. The right tog depends on the room temperature. As a guide:
| Room temperature | Sleeping bag tog | Under the bag |
|---|---|---|
| 24°C or above | 0.5 tog | Nappy and short-sleeved vest |
| 21–23°C | 1 tog | Short-sleeved vest |
| 18–20°C | 2.5 tog | Long-sleeved vest or sleepsuit |
| 16–17°C | 2.5 tog | Long-sleeved sleepsuit |
| Below 16°C | 3.5 tog or add a layer | Sleepsuit plus vest |
How to check if your baby is too hot
Check your baby’s temperature by feeling the back of their neck or chest — not their hands or feet, which are naturally cooler. If the back of the neck feels hot or sweaty, your baby is too warm and needs a layer removed or the room cooled. A baby who is too cold will wake and cry — overheating is the greater risk because babies cannot regulate their temperature as effectively as adults.
⑤ Room Sharing — The First Six Months
The NHS recommends that your baby sleeps in the same room as you for at least the first six months — for both daytime naps and night sleeps. Research shows that room sharing (without bed sharing) reduces SIDS risk by up to 50 percent. The mechanism is not fully understood but is thought to involve the parent’s breathing influencing the baby’s breathing patterns and increasing arousal.
Practical room sharing options
The most practical way to room-share is with a bedside crib that attaches to your bed frame — this gives the baby a separate, safe sleep surface at bed height, making night feeds significantly easier without requiring you to leave the bed. Freestanding cribs and Moses baskets also work for room sharing but require moving to a different position for feeds. After six months, your baby can move to their own room with a full cot. Use a baby monitor once the baby moves rooms.
What happens after six months?
After six months, SIDS risk reduces significantly and many families choose to transition the baby to their own room. The move is not compulsory — room sharing beyond six months is safe and some families continue it for longer. When transitioning, use our Safe Sleep Checker to confirm the new room setup before the first night, and set up a baby monitor so you can hear the baby. Our baby sleep guide covers the room transition in detail.
⑥ Bed Sharing — The Honest Guidance
Bed sharing — sleeping in the same bed as your baby — is practised by many families and is common in many cultures worldwide. The NHS guidance is that bed sharing is significantly safer on a firm, flat adult mattress than on a sofa or armchair, but carries higher SIDS risk than a baby sleeping in their own cot in the same room.
When bed sharing carries the highest risk
The risk from bed sharing is significantly higher when any of the following apply: a parent smokes (even outside), a parent has consumed alcohol or sedating medication, a parent is very tired, the baby was premature (born before 37 weeks), or the baby weighed under 2.5 kg at birth. In any of these circumstances, the NHS advice is clear: do not bed share.
The C-position for safer bed sharing
If you choose to bed share outside of the above risk factors, the Lullaby Trust recommends the “C-position”: mother curled around the baby with knees below and arm above, creating a protected space that prevents rolling onto the baby and reduces the risk of the baby moving toward pillows. The baby should be on a firm mattress, on their back, away from pillows, and without covers over them. This does not eliminate risk — it reduces it relative to unplanned or sofa bed sharing.
Planned vs unplanned bed sharing
The most dangerous bed sharing is unplanned — falling asleep on a sofa or chair while feeding a baby. If you are likely to fall asleep while feeding, prepare a safe sleep space first so that if you do fall asleep, the baby can be moved quickly and safely. A bedside crib at mattress height makes this transfer much easier.
⑦ SIDS — What It Is and What Reduces Risk
Sudden Infant Death Syndrome (SIDS) is defined as the sudden, unexpected death of a baby under 12 months that remains unexplained after a thorough investigation including a post-mortem examination. It is most common between 2 and 4 months of age, and more common in male infants. It occurs more often in winter, which is associated with overheating and respiratory infections rather than cold itself.
The triple risk model
Current research suggests SIDS occurs at the intersection of three factors: a vulnerable baby (who may have an underlying neurological susceptibility), a critical developmental period (the first six months when breathing regulation is still maturing), and an external stressor (such as front sleeping, overheating, or exposure to smoke). Removing the external stressor — which is the part parents can control — is how safe sleep recommendations reduce risk.
What significantly increases SIDS risk
Front or side sleeping position, exposure to tobacco smoke, overheating, soft sleep surfaces, loose bedding or objects in the sleep space, sofa or armchair sleeping, bed sharing with a smoker or someone who has consumed alcohol, and premature birth or low birth weight all independently increase risk. The combined effect of multiple risk factors is multiplicative, not additive.
What significantly reduces SIDS risk
Back sleeping, room sharing in a separate cot, a firm clear sleep surface, maintaining 16–20°C room temperature, breastfeeding, not smoking, and using a dummy during sleep all reduce risk. Dummies during sleep are associated with reduced SIDS risk — the mechanism is not fully understood but is thought to involve keeping the airway open and increasing arousal. If your baby uses a dummy, offer it for each sleep but do not force it or replace it if it falls out during sleep.
⑧ Full Safe Sleep Checklist
Use this checklist before every sleep, particularly in the early months when establishing routines. Our interactive Safe Sleep Checker also walks through each point with guidance on what to do if anything is not correct.
Safe sleep does not need to be complicated
The core of safe sleep is simple: back to sleep, on a firm flat surface, in a clear cot, in your room, at the right temperature. These five things cover the majority of SIDS risk reduction. Everything else — the specific mattress brand, the sleeping bag brand, the exact tog — matters less than getting these fundamentals right consistently.
Use our Safe Sleep Checker to confirm your specific setup, and our baby sleep guide for practical guidance on establishing routines, managing wake windows, and navigating the transition to a separate room when the time comes.
