The Link Between SIDS and Serotonin Levels

Abnormal levels of serotonin may cause sudden infant death syndrome.

Baby Sleeping
WestEnd61/Getty Images

Sudden infant death syndrome (SIDS) is the leading cause of death in infants between the ages of 1 and 12 months in the developed world. Despite this staggering statistic, the cause (or causes) of SIDS remains largely a mystery. However, research may be shedding light on a possible cause of at least some of these cases. 

What Causes SIDS?

The exact cause of SIDS is unknown. Most likely there are many reasons that babies die unexpectedly that we have not discovered yet.

It could be that there are things that cause the deaths of infants that are unrelated to each other. Or it's possible that there are underlying causes in a majority of the deaths that researchers have yet to identify. SIDS is a heartbreaking and frustrating condition for the millions of people it has affected. Because it is such a mystery, there has been significant research and work to try to decrease the number of deaths from SIDS and determine if there is something specific that may cause it.

A study published in 2010 based on post-mortem examinations of babies that died from SIDS found decreased levels of serotonin in the brains of many of the infants. However, research published in 2017 found increased levels of serotonin in the blood of babies that died from SIDS. These studies may seem contradictory but taken together, this could indicate that abnormal levels of serotonin – whether increased or decreased – could play a role in the deaths of infants that were previously unexplained.

What Is Serotonin?

Serotonin is a chemical released from nerve cells—called a neurotransmitter—that affects nearly every part of the body. It helps regulate eating, sleeping, and digesting. It is largely found in the digestive system but is also present in blood cells and in the central nervous system.

Serotonin regulates many different parts of the body and is responsible for many functions. A few things that it affects include:

  • Mood
  • Wound healing
  • Bone health
  • Stimulating nausea
  • Controlling bowel movements and bowel function
  • Blood clotting
  • Sexual function

Serotonin is responsible for stimulating the brain for waking and sleeping. It is thought that abnormal levels could make it difficult for an infant to wake when she is breathing inefficiently. When a baby is sleeping face down or has her face against a soft object, she may rebreathe too much carbon dioxide. While an infant with normal levels of serotonin may wake enough to turn her head or roll over, it is thought that babies with abnormal levels may not.

What You Can Do

Losing a child is one of the most traumatic events that can happen to any parent. Not knowing how or why it happened is a cruel and heartbreaking reality for those that lost their children to SIDS. At this point, these deaths are largely unpreventable. However, there are things you can do to reduce the risk that your child will die from SIDS.

  • Put your baby on his back to sleep—this recommendation alone has significantly reduced the rate of SIDS deaths in recent decades.
  • Avoid co-sleeping.
  • Place your baby in a crib with a fitted sheet only. Remove blankets, stuffed animals, pillows and any other loose items. These can cover your baby’s face and cause suffocation.
  • Avoid smoking and drinking during pregnancy—research has shown that these practices can decrease the levels of serotonin in infants, which may put them at higher risk for SIDS. They are also responsible for other health risks for infants, children, and adults.
  • Using a pacifier may help keep a baby’s airway open. However, there is no need to force the use of a pacifier if your baby is naturally a thumb-sucker or does not like the pacifier. Use of a pacifier for breastfed infants is not recommended until 1 month of age due to nipple confusion.
  • Don’t put your baby to sleep on a chair, sofa, water bed, or other soft surface.
  • The safest place for your baby to sleep is in the same room with you—about an arm's length away—in his own crib.
  • Avoid using thick or fluffy crib bumpers. If you use bumpers, they should be thin, tight-fitting, and secure.

All of these recommendations are made to reduce the chance that your baby will get stuck in a position where she is rebreathing her own carbon dioxide. Based on the results of these studies, researchers believe it’s possible that while infants with normal serotonin levels may wake and move when this occurs, those with abnormal serotonin levels may not. When a baby is stuck in this position and does not wake, it can lead to her death from lack of oxygen or too much carbon dioxide. This hypothesis has not been proven, but more research is being conducted based on the results of these studies.

A Word From Verywell

SIDS is a tragic and heartbreaking way to lose a child. There is still so much that we don't know about why infants die for no apparent reason. Research into possible causes has shed some light onto one of the potential sources. It's quite possible—and likely—that there are other reasons infants die unexpectedly as well. Hopefully we will have clearer answers and ways to prevent these deaths in the near future.

Sources:

Bright FM, Byard RW, Vink R, Paterson DS. Medullary Serotonin Neuron Abnormalities in an Australian Cohort of Sudden Infant Death Syndrome. J Neuropathol Exp Neurol. 2017;76(10):864-873. doi:10.1093/jnen/nlx071.

SIDS Infants Show Abnormalities in Brain Area Controlling Breathing, Heart Rate Serotonin-Using Brain Cells Implicated in Abnormalities. https://www.nichd.nih.gov/news/releases/pages/sids_serotonin.aspx.

SIDS Linked to Low Levels of Serotonin. National Institutes of Health (NIH). https://www.nih.gov/news-events/news-releases/sids-linked-low-levels-serotonin. Published August 12, 2015. 

Ways To Reduce the Risk of SIDS and Other Sleep-Related Causes of Infant Death. https://www.nichd.nih.gov/sts/about/risk/Pages/reduce.aspx. 

Continue Reading