Sudden infant death syndrome (SIDS) refers to the unexpected, unexplained death of a child less than one year old. SIDS is rare during the first month of life. It peaks at 2 to 4 months of age, then gradually decreases.

Experts do not know the exact cause of SIDS. Many theories exist. Potential causes include:

  • Abnormalities in a section of the brain that controls breathing during sleep and waking
  • Abnormalities in the control of heart rhythm
  • Changes in how serotonin, a neurotransmitter, functions in the brain
  • Changes in some components of the immune system
  • Inadequate arousal response to breathing obstruction or asphyxia—a lack of oxygen or excess carbon dioxide in the body caused by interruption of breathing; may cause unconsciousness

Brainstem
brainstem
Area of the brain involved in regulation of breathing.
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