When people are in comas, they are unconscious and cannot communicate with their environment. However, the brain of a coma patient may continue to work. It might “hear” the sounds in the environment, like the footsteps of someone approaching or the voice of a person speaking.

Stopping Life Support Choosing to remove life support usually means that the person will die within hours or days. The timing depends on what treatment is stopped. People tend to stop breathing and die soon after a ventilator shuts off, though some do start breathing again on their own.

More invasive life support, such as heart/lung bypass, is only maintained for a few hours or days, but patients with artificial hearts have survived for as long as 512 days.

Usually, comas are more like twilight states – hazy, dreamlike things where you don’t have fully formed thoughts or experiences, but you still feel pain and form memories that your brain invents to try to make sense of what’s happening to you.

Patients in a coma appear unconscious. Their brains often show no signs of the normal sleep-wakefulness cycle, which means they are unlikely to be dreaming. Yet many people who have recovered from comas report dreams into which something of the outside world penetrated.

Comas can last from several days to several weeks. In more severe cases a coma may last for over five weeks, while some have lasted as long as several years. After this time, some patients gradually come out of the coma, some progress to a vegetative state, and others die.

When your survivor emerges from her coma, she likely will have little or no short-term memory. She may be disoriented, agitated, angry, impulsive, or extremely emotional. She may be disinhibited, demonstrating a complete disregard for social conventions.

Comas are caused by damage to the brain, specifically the diffused bilateral cerebral hemisphere cortexor the reticular activating system. This area of the brain controls arousal and awareness.