According to the American Society of Chemists, the feeling before death is compared to the feeling when you watch a very scary horror movie as they found that the brain reacts in the same way in both cases.
Fear actually prepares us to react when we are in danger. Furthermore, there is a part in the brain named thalamus, which is very sensitive to stress and with a chemical reaction in the brain we come into a state of “flight” or “fight” thankfully to the hypothalamus.
How we get this strength?
The hypothalamus stimulates the adrenal gland to secrete adrenalin. In this way, the body is prepared for action.
The adrenalin travels to the liver when the secretion of sugar in the blood is stimulated. The strength is gained in this way.
If this does not help, just like in the horror movies people start screaming. The interesting part here is that the screams are not perceived with the same brain part as the speech. And also, another interesting fact is that when we hear someone screaming, the sound goes from our ears directly to the part of the brain named amygdale.
Now, imagine that you are in the horror movie and someone is chasing you with an axe to kill you.
You start screaming, but that won’t help. What you will feel next if the killer catches you and stabs you with the axe, you will feel pain but not the same pain as you are used to, but a kind of pain which will send a message to the brain that something terrible is going on and that it should never be repeated.
The killer stabs you in the neck, your heart will stop working and you will eventually stop breathing too (clinical death). But in this this moment, your brain actually works and that is why some people said that they have seen light or other strange things (people who have survived clinical death). But if there is no emergency help arrives, the brain will stop working as well and biological death comes along.