To preface, this research was done on small population of infants, and has yet to be redone on a larger population of infants. Most researchers see this as a preliminary study, that needs to be investigated further, with better patient demographics.

According to research done by 3 scientist in Australia, there's a specific enzyme that has been cross linked in multiple infants who have suffered from SIDS. Granted the observation showed that the enzyme level was low in comparison to other infants.

"Carmel Harrington and two co-authors thought the enzyme might play a role in SIDS. Sure enough, in dried blood spots that had been taken in the first day or two of life, they found that in 67 infants who later died of SIDS, levels of the enzyme were on average only 73 percent as high as in children who died of other causes" (Hurley, 2022).

This enzyme, butyrylcholinesterase, helps regulate autonomic functions like breathing, heart rate, etc. So, a lack of said enzyme can be reason why in an infant's sleep, their more likely stop breathing and eventually pass.

Infants who die of SIDS are believed to have a dysfunctional autonomous nervous system: When their blood-oxygen level dips during sleep, they remain still, rather than gasping, crying…" (Hurley, 2022).