What is this news item mainly about? [originaltext] Sudden Infant Death Syndr

Sudden Infant Death Syndrome is considered the most common cause of death among babies younger than one year old. The reason for these deaths is often a mystery. Now researchers have discovered something unusual in the brains of many of these babies. Sudden infant death can occur without warning, but there are some common factors associated with what is also called "crib death".
    Researchers from Children’s Hospital of Boston, Massachusetts and Harvard Medical School think they may have discovered a cause for crib death. What they found were abnormalities in the brain stems of 31 babies and 10 infants who had died of SIDS. (28) Their results indicate an imbalance in the neurotransmitter called serotonin that influences the baby’s breathing, temperature and ability to wake up. The danger occurs when babies born with too much serotonin which is placed on their brain stems to sleep.