What exactly is a coma and what happens to you when you’re in one?

You’ve probably seen comas on soap operas and other TV shows, but what is a coma, and how does it work?

A coma occurs when conscious activity is impaired by a brain injury or the reduction of blood flow to the brain. There are two parts of the brain that must be functioning for someone to remain conscious: the cerebral cortex, the grey outer part of the brain, and the reticular activating system, which is in the brainstem. If either aren’t functioning, a person will slip into a coma.

There are numerous causes for comas. Some of the most common include excessive drug consumption, lack of oxygen in the brain, low blood sugar, increased carbon dioxide in the blood, a traumatic brain injury or a hemorrhage. Sometimes people are placed in medically induced comas to reduce further brain injury and swelling.

By far the largest cause of a coma is drug consumption, which makes up 40% of cases. After this, it is lack of oxygen in the brain, which makes up 25% of cases. The third most common cause for a coma is a stroke, at 20%. Other causes can be attributed to the final 15% of cases.

People in comas are alive and in some cases can breathe on their own, but they can’t respond to stimuli. The brain of a person in a coma is active but only at a base level, much like how it is when you are asleep. But all comas are different.The Glasgow coma scale assigns a ranking to a coma on a scale from 3 to 15, where 3 is a deep coma, and 15 is awake and responsive. A score of 8 is the earliest point in which someone is considered comatose, instead of in a similar, more aware condition.

Doctors provide three steps of immediate treatment to newly diagnosed comatose patients. They are referred to as the “ABC,” meaning airway, breathing and circulation. After this is an assessment of the patient to determine the cause of the coma. Then comatose patients are put on IV nutrients so that they don’t starve to death. And in cases where the patient can’t breathe on their own, they are put on a ventilator.

So do people actually remember being in a coma? It’s rare, but it’s more common that people remember things that didn’t actually happen. Some people who have been in comas have reported vivid dreams and hallucinations. And in some cases, what’s going on around the comatose person gets incorporated in these dreams.

Researchers suggest that these hallucinations are the brain’s attempt of making sense of an outside world that’s barely felt. But little is still known about what patients experience during a coma.

However, functional MRI scans can reveal information about brain activity in comatose patients. Certain cases have shown that a comatose patient’s brain activity was “robust” when a family member spoke to them.

Sometimes, there is a way to wake someone from a coma. This is done through reversing the coma’s cause or applying medication that will prevent brain swelling. If the coma has been caused through cardiac arrest, then inducing hypothermia can wake a patient. In fact, inducing hypothermia has been shown to improve eventual recovery rates for all coma patients. Sadly, there is often no effective treatment to wake some people up from a coma. Either the patient wakes up or they don’t. But hopefully with more research we can learn more about the medical mystery of comas.

Unlike many films, when someone does wake up from a coma, it is not an instantaneous experience. Often in the first days, patients only wake up for a few minutes, with this time gradually increasing every day. Also, people regularly experience physical, intellectual and psychological difficulties after waking from the coma. Some do not ever regain the level of intellect and mobility that they had before their coma.

The longest recorded time for someone being in a coma is 42 years. This person, American Edwarda O’Bara, never recovered and died in her comatose state in 2012. The longest time someone has been in a coma and woken up is contentious due to the prolonged recovery and differences in interpretation. Some sources cite two people, American Terry Wallis and Polish Jan Grzebski as both being in comas for 19 years. However they were both considered in a minimally conscious, vegetative state for much of this time. If someone has been in a coma for more than 4 months, the chances of them recovering are less than 15%.