Thermal stress (overheating) has been implicated in SIDS and SUDI for many years and avoiding overheating has been one of the strategies to reduce risk of SUDI.
Key points on how much bedding should be placed on baby in a sleeping environment
- Dress baby and use layers as you would dress or use layers yourself: to be comfortable, neither too hot nor too cold.
- Research has shown that baby’s risk of dying suddenly and unexpectedly is increased if baby is sleeping on the tummy and that risk is even further increased if baby is sleeping on the tummy under heavy bedding or if baby’s head becomes covered by bedding in any position. Babies manage heat loss very efficiently when placed on the back to sleep with the head uncovered. Sleep baby on the back and keep baby’s head uncovered during sleep to reduce baby’s risk of sudden unexpected death.
- Make up baby’s bed so baby sleeps at the bottom of the cot and the blankets can only reach as far as baby’s chest, ensuring baby cannot move down during sleep and get his/her head covered by bedding.
- Consider using a safe baby sleeping bag (one with fitted neck, armholes or sleeves and no hood).
- Dress baby for sleep and add/remove lightweight blankets to ensure baby’s back or tummy feels comfortably warm to the touch.
- Remove hats, bonnets, beanies and hooded clothing from baby’s head as soon as baby is indoors.
Since the introduction of public health programs promoting ‘back-to-sleep’ to reduce the risk of SUDI, there has been a significant reduction in the number of babies dying suddenly and unexpectedly.1 However, tragically, around 113 babies die suddenly and unexpectedly every year in Australia2 and it is important to keep following evidence-based recommendations on ways to avoid risk factors related to baby’s sleep environment.3-4
The association between overheating and SUDI has been known for several years particularly if baby’s head is covered.5-8 Current research confirms that if your baby becomes too hot, the risk of SUDI is increased.9 Overheating can be caused by room heating, high body temperature, excessive clothing or bedding and head covering.10 To reduce the risk of this, Red Nose recommends that you, as baby’s parent or carer, use your own judgement, taking into account factors such as where you live (climate, whether it is summer or winter), whether you have heating in the house, and whether baby has a cold or minor illness (which may cause their temperature to rise).
A useful guide is to dress baby as you would dress yourself: to be comfortable, neither too hot nor too cold. If baby has a minor illness and has a temperature it is common for parents or carers to overdress baby for sleep11 but in fact, fewer bedclothes should be used or, at times, none at all. If parents or carers are worried that baby is ill they should talk to their baby’s doctor and have the baby assessed.
Both hyperthermia (unusually high body temperature) and hypothermia (unusually low body temperature) are important to avoid during infancy.8
Baby’s face and head should always remain uncovered. Baby’s head (particularly the face) is the main route for heat loss.12 Overheating has been found to be related to SUDI and the risk of overheating is increased if baby is sleeping on the tummy.5 This is especially dangerous if baby is under heavy bedding as, if baby should roll over onto the tummy, then the risk of overheating is even further increased. In fact, research has shown that babies sleeping on the tummy are at ten-fold the risk of SUDI while sleeping in a heated room.6
Increased temperature has been shown to alter infant physiology by increasing respiratory and heart rate and in some studies the frequency of central apnoeas. Increased temperature, whether due to head covering or by increasing room temperature depresses arousal responses and reduces autonomic control of heart rate.13-16 Both impaired respiratory control, arousal from sleep and autonomic cardiovascular control have been implicated in the final mechanism of SIDS.9,17
Bedding for babies who have a cold
Research has shown that babies with symptoms of a common cold are often given more bedding than they need due to care giver concerns that babies showing signs of a cold need to be kept very warm.11 In fact, providing assistance to babies with a common cold to effectively regulate their temperature is very important. This can be best achieved by placing them on the back to sleep with the head uncovered and removing some bedding or clothing. If baby is overly warm to touch, or showing signs of heat stress (irritability, looking unwell, floppy, drier skin, refusing to drink or having fewer wet nappies than usual) then see your doctor or health professional immediately.
Can we say exactly how many blankets to use when baby is placed to bed?
The simple answer is – No. Red Nose recommend that rather than state how many bedclothes can be safely placed on a baby, parents can work out the amount of bedding to be used after considering these factors:
- The room temperature where baby is sleeping.
- How hot does the baby feel? A good way to check baby’s temperature is to feel baby’s back or tummy (don’t worry if baby’s hands and feet feel cool - this is normal).
- Whether the baby has a cold or infection or another special need.
- Consider how many layers that you as the baby’s carer are wearing comfortably.
Sleeping baby in a safe baby sleeping bag: one designed especially for baby with fitted neck and armholes and no hood, has a number of features that help baby sleep safely. Research has shown that sleeping bag use will reduce the risk of bedclothes covering the baby’s face, will delay baby rolling onto the tummy during sleep until baby is past the age of peak risk of SUDI, promotes supine sleep as the zipper opens to the front18 and will keep baby’s temperature at a more constant level while sleeping at home.19
If blankets are being used instead of a sleeping bag, it is best to use light weight blankets in layers that can be added or removed easily according to the room temperature and which can be tucked underneath the mattress. (For more information on how to prepare baby’s cot for sleep, see brochure Making Up Baby’s Cot).20
Always remove hats or bonnets or beanies from baby as soon as you come indoors or enter a warm car, bus or train, even if it means waking the baby.21 Never use electric blankets, wheat bags or hot water bottles for babies.
For more information on this topic, see the Red Nose Information Statement on Room Temperature.22
The Red Nose Safe Sleeping program is based on scientific evidence and was developed by Australian SUDI researchers, paediatricians, pathologists, and child health experts with input from overseas experts in the field. The 80% drop in SUDI deaths and the more than 9,000 lives that have been saved is testament to the effectiveness of the program.
For further information on Safe Sleeping phone us on 1300 998 698.
Red Nose. National Scientific Advisory Group (NSAG). (2016). Information Statement: Bedding amount recommended for safe sleep. Melbourne: Red Nose. This information statement was first posted in 2013 and updated in July 2016.
View the references for this article here.