How long does our Brain works after Heart stops beating

We all know that our brain works through electrical signals / impulses travelling through neurons. Brain is one of the most mysterious organs of human body, which is still not completely understood by medical science. From past few decades some researchers are conducting researches on its functioning. When a person dies, his brain can still work for some time due to some oxygenated blood present in it and electrical impulses travelling inside brain. These things are sufficient to keep the brain alive even after heart stops beating. It the person revives through some medical intervention by making his heart beat before brain dies, then it is called near-death-experience (NDE).

Actual Death of a person can only be considered when all levels of consciousness is lost and all electrical activity shuts down completely. Electrical activity inside the brain can be measured by scientific instruments.

How long does our brain works after Heart stops beating

According to some researches it takes 3 to 5 minutes for all electrical activity to seize inside brain after heart has stopped beating. However some researchers are in dilemma if consciousness also seizes with electrical activity.

Depolarization is a shift in electrical charge distribution among cells. Chemical changes that leads to actual death of brain begin with depolarization of brain cells. As the depolarization spreads across the brain and final wave of electrical activity travels through brain, it is called "spreading depression". According to researchers this "spreading depression" shuts down the brain completely. Once this condition has occurred then even restarting the heart no longer works, as damage to the brain becomes irreversible.

Where this research will be used ?
This research can play a crucial role in reviving a person who has just passed away due to heart failure. It can also help in such organ transplants where blood supply to brain needs to be stopped for a very short period of time.

How does a person feel when his heart stops but brain is not dead ?
Collecting such experiences is a major part of such medical researches. Such researches of some previous decades reported experiences like flashes or tunnels of light, which were anecdotal in nature. Such experiences are collected from such patients who revived after medical intervention minutes after their heart stopped beating. In some recent researches patients reported peaceful, fearful or feeling being dragged under water. Some survivors reported hallucinations, while some heard their own death being declared by doctors. Most of such memories remain only for a short time, but some survivors can recall all conversation that occurred between doctors and nurses while trying to resurrect him/her.

Note: Some experts believe that a healthy person can revive even hours after death. But in such cases there are chances of substantial amount of brain damage.