Does sleep position alter the risk of SUDEP?

Photo: Dr. Elizabeth Donner

It is well documented that SUDEP occurs most often in relation to sleep. People who die of SUDEP are usually found dead in bed in the morning, in the facedown position. This position is also referred to as the prone position. Can we conclude from this that the sleep position somehow affects a person’s risk of SUDEP?

In February 2015, the medical journal Neurology, published a study conducted by neurologists at the at the University of Chicago[1]. These researchers performed a systematic review and meta-analysis of all publications in the medical literature that reported cases of SUDEP, including the details of the position of the body at the time they were found deceased. Twenty-five studies were reviewed, including 253 cases of SUDEP in which the body position was noted. Seventy-three percent of these individuals were found in the prone position. When the researchers examined the age of the deceased and their position at death, they found that people less than 40 years of age at death were more likely to be found in the prone position. They also looked at 21 cases of SUDEP that occurred from the awake state. Even in these cases, 62% of the people that died from the awake state were found in the prone position upon death. 

What does this study tell us? First, this study confirms that the majority of people that die from SUDEP are found in the prone position. It also suggests this may be more common in people under 40 years of age, however the study cannot explain why this may be the case. The authors postulate it may be that people under 40 are more likely to be living and sleeping alone and not have someone by their side to offer them first aid after a seizure. Perhaps, the risk of SUDEP is reduced if a person is put on their side or back following a seizure. However, we cannot draw that conclusion from this study. 

In the same issue of Neurology, Drs. Dworetzky and Schuele point out that this study did not present us with information regarding how often people with epilepsy have a seizure and roll into the prone position and do not die[2]. Without this information, it is difficult to be certain about whether being in the prone position truly increases the risk of SUDEP. 

The observation that most SUDEP deaths occur in the prone position has lead doctors and scientists to point out the similarity to Sudden Infant Death Syndrome (SIDS). This may be helpful in advancing our understanding of the mechanism of death in SUDEP. Researchers are using animal models of SUDEP to explore these connections. 

In the case of SIDS, we know that putting babies to sleep on their back, avoiding the prone position, has resulted in a dramatic decrease in the number of SIDS cases. Could this work for SUDEP? To answer this we need to recognize the significant differences between SIDS in young infants and SUDEP in older children and adults. The most important difference is that young infants do not yet have the ability to roll over. For this reason, when an infant is placed on their back to sleep, they will stay in that position for the remainder of the sleep period. In contrast, children and adults move during sleep, often changing from the prone to faceup position and back again. Further, it is possible that when a person with epilepsy has a seizure, they will roll over as part of the seizure event. Thus, regardless of how we go to sleep, we may end up in a different position during the night. And, in the case of people with epilepsy, it is possible that the seizure may cause them to roll into the prone position. Consequently, we cannot draw from this study that going to sleep on one’s back will reduce the risk of SUDEP. 

Despite the fact that we cannot conclude that going to sleep on one’s back will reduce SUDEP risk, this study does offer important clues as to what may be causing SUDEP in some cases. As scientists, physicians and families work together to learn more about SUDEP we get closer to a better understanding of this devastating condition. By critically examining all cases of SUDEP over time, we will learn how to prevent more tragic deaths.

References:

  1. Liebenthal JA, Wu S, Rose S, Ebersole JS, Tao JX. Association of prone position with sudden unexpected death in epilepsy. Neurology 2015;84:703-9.
  2. ​Dworetzky B, Schuele SU. Facing up to SUDEP. Neurology 2015;84:643-4.

 

Dr. Elizabeth Donner is a Pediatric Neurologist at the Hospital for Sick Children, Toronto and Associate Professor at the University of Toronto.  She conducts SUDEP research, is implementing a pediatric SUDEP registry and is a co-founder of SUDEP Aware.