The body doesn’t just decide to go into a state of coma. It typically occurs because of some traumatic assault — an underlying medical condition, drug overdose, or as a result to an injury, such as head trauma. Sometimes doctors induce a coma, such as with Arizona Congresswoman Gabrielle Giffords, who was shot in the head in 2011 during an alleged assassination attempt.
A medically induced coma effectively shuts down brain function and gives the brain time to heal without having to expend energy to perform cognitive tasks. This helps reduce swelling and protects the injured part of the brain most at risk when no other treatment has worked.
It's important to note a medically induced coma is not the same thing as sedation. A medically induced coma is a very deep unconscious state, whereas sedation, as used in surgery or in other medical procedures to keep a patient comfortable ...
https://www.empowher.com/coma/content/what-coma