Sudden Infant Death Syndrome (SIDS) is the unexpected, unexplained death of a seemingly healthy baby less than one year old. SIDS is sometimes known as crib death because the infants often die in their cribs. SIDS is the leading cause of death in babies between 1 month and 1 year old.
What is SIDS?
SIDS is defined as the sudden death of an infant under one year of age that remains unexplained after a complete investigation. This investigation includes an autopsy, examination of the death scene, and review of the clinical history.
Some key facts about SIDS:
- SIDS is the leading cause of death in babies between 1 month and 1 year of age.
- Most SIDS deaths occur when babies are between 1 and 4 months old.
- SIDS is more common in boys than girls.
- Babies born prematurely or at a low birth weight have a higher risk of SIDS.
- SIDS deaths peak in the winter months.
While the cause is unknown, SIDS may be associated with defects in the parts of an infant’s brain that control breathing and arousal from sleep. Risk factors include prone sleeping, soft bedding, smoking during pregnancy, and overheating.
Can night waking help prevent SIDS?
There is some evidence that night waking may help protect against SIDS. Studies have found that babies who die from SIDS tend to sleep more deeply than babies who survive. One theory is that babies who wake up more easily at night from noise or other stimuli may be less likely to experience whatever biological abnormalities lead to SIDS.
A 2020 study published in the journal eBioMedicine analyzed overnight recordings of 79 infants. It found that those who went on to die of SIDS had fewer night wakings and longer periods of deep sleep compared to the control group of infants that survived.
Another study monitored the heart rates and breathing of 45 newborn babies during sleep. The babies who experienced SIDS had fewer night wakings, less frequent heart rate changes, and lower heart rate variability compared to babies who did not have SIDS.
While these studies show an association between fewer night wakings and a higher risk of SIDS, they do not prove causation. More research is needed to determine if night waking itself helps prevent SIDS.
Should parents try to wake their babies at night?
Based on the current evidence, there are no guidelines recommending that parents wake their babies intentionally during the night to prevent SIDS. In fact, this could be harmful if it prevents the infant from getting enough sleep.
However, parents should follow other safe sleep practices that may incidentally lead to more night wakings. This includes:
- Placing babies on their back to sleep. Babies sleep more lightly on their backs compared to their stomachs or sides.
- Keeping babies close but separate. Room sharing without bed sharing may help arousal.
- Avoiding soft bedding, blankets, bumpers that could impair arousal.
- Not overheating the room. Excess heat can deepen sleep.
Following these guidelines creates a safer sleep environment that may make it more likely for a baby to wake up normally in the night.
Tips for handling night wakings
While frequent night wakings can be normal and protective for infants, lack of sleep is exhausting for parents. Here are some tips for coping with night wakings:
- Take turns. Alternate middle of the night duties with your partner so each person can get longer sleep stretches.
- Sleep when baby sleeps. Nap during the day when possible.
- Accept help. Let family members or friends take the baby for a few hours so you can rest.
- Focus on safety. Remind yourself that night wakings may protect against SIDS.
- Don’t try to force sleep. Respond to the baby’s cues instead of ignoring cries.
Night wakings tend to decrease as babies get older and their sleep matures. If night wakings remain frequent after 6 months, consult your pediatrician.
Does swaddling help prevent SIDS?
Swaddling involves wrapping a baby snugly in a light blanket or special swaddling cloth with their arms close to their bodies. Many babies sleep better when swaddled as it prevents startling and reminds them of the confined space of the womb.
Research shows swaddling can help promote sleep and decrease crying. But there are some risks, including overheating and hip dysplasia if the legs are too tight. Once a baby shows signs of trying to roll over, swaddling should no longer be used.
In terms of SIDS prevention, a meta-analysis of four studies found a decreased SIDS risk with swaddling. However, the American Academy of Pediatrics recommends the following precautions:
- Only swaddle with a light, breathable blanket.
- Always place baby on their back.
- Stop swaddling as soon as baby shows signs of trying to roll.
- Avoid loose blankets around the face.
- Do not use Swaddling if baby has a fever, illness, or is over 2 months old.
With these precautions, the AAP concludes that the benefits of swaddling likely outweigh the risks in the first 2 months of life. More research is needed on the effects of swaddling and SIDS risk after 2 months of age.
What is the Back to Sleep campaign?
The Back to Sleep campaign was launched in 1994 by the National Institute of Child Health and Human Development (NICHD) to educate parents and caregivers about SIDS risk factors and prevention. Its key messages include:
- Always place babies on their backs to sleep, for naps and at night. (“Back to sleep” refers to back sleeping position.)
- Use a firm sleep surface. Do not use soft bedding.
- Keep soft objects and loose bedding out of the crib.
- Do not smoke during pregnancy or allow smoking around baby.
- Room share without bed sharing.
This public health campaign has been highly effective. SIDS rates have dropped by over 50% since 1994 when the campaign began:
| Year | SIDS Rate (per 1,000 live births) |
|---|---|
| 1990 | 1.4 |
| 2000 | 0.56 |
| 2010 | 0.54 |
| 2020 | 0.37 |
While SIDS has not been eliminated fully, the substantial decline in rates demonstrates the effectiveness of the Back to Sleep campaign’s straightforward public health messaging.
What is the latest SIDS research?
Some promising areas of SIDS research include:
- Brainstem abnormalities – Studies of babies who died from SIDS have found possible defects in brainstem regions controlling cardiac function, breathing, and arousal. More research is needed into the origins of these abnormalities.
- Serotonin – Infants who die from SIDS may have fewer serotonin receptors which help regulate breathing, heart rate, sleep cycles, and body temperature.
- Genetics – There are likely genetic mutations that may impair an infant’s ability to respond to breathing or cardiovascular challenges during sleep.
- Toxic gases – Exposure to low levels of toxic gases like carbon dioxide may affect an infant’s arousal mechanisms. More data is needed.
While progress has been made, the exact causes of SIDS are still unclear. Continued research into brain function, genetics, and environmental factors during sleep can help uncover new ways to further reduce SIDS risks.
Conclusion
Night waking is common in infants and may provide a protective effect against SIDS according to some studies. While intentional waking is not recommended, following safe sleep guidelines can help create an environment that allows babies to wake up normally. Swaddling can also promote better sleep when used correctly in the first 2 months. SIDS rates have fallen dramatically thanks to research and public health campaigns, but there is still more work to do to understand the underlying biological causes.