Researchers now believe that the silent killer in babies, Sudden Infant Death Syndrome (SIDS), could be caused by an imbalance of serotonin in the brain. A new research done in mice pointed to this new clue when imbalanced levels of serotonin, a chemical mainly known to influence one's mood, have lead to death in mice.
Mice were genetically engineered to overproduce the brain chemical serotonin. This overproduction lead to died at an early age but before dying the mice developed symptoms similar to those of sudden infant death syndrome. Such behaviour suggested improper regulation of serotonin may cause SIDS in humans.

Most of the mice that died were unable to regulate their heart rates and body temperatures.

Researchers believe that these findings could prompt clinical research to develop diagnostic tests to try to identify which kids were most likely to die of SIDS.

SIDS, in which seemingly healthy babies between 1 month and 1 year old die without warning or explanation, kills around 2,700 infants in the U.S. every year.

The mice were part of a study on serotonin's role in aggression and anxiety, but after they began dying, a scientist suggested the deaths might be related to SIDS.

This was a chance discovery since the mice were part of a study on serotonin's role in aggression and anxiety and not SIDS. Serotonin, besides mood, regulates bodily functions such as temperature, respiration and heart rate.

Previous studies have also showed that infants who died of SIDS had abnormal serotonin-producing cells in their brain stems.