What causes people to faint?

We often see that people faint on hearing some sad news or on getting frightened suddenly. They get drenched in their sweat and their bodies become cold. Their faces turn pale. Physical consciousness diminishes. Unconsciousness can be caused not only by a shocking news or terrible fear, but by many other factors also. People may faint because of confinement in a close and poorly ventilated room,

or because of hunger, fatigue, severe pain, emotional shock or for many other reasons. Now the question arises: why do people become unconscious?
In order to know the reasons for fainting, it is essential to know what consciousness is. For the normal functioning of the brain, it is essential that there should be proper circulation of activities remain normal. The normal functioning of the brain is in fact consciousness. If there is some obstruction in the supply of blood to the brain, the common physical processes get disturbed. Whatever may be the cause of fainting, man will become unconscious when normal supply of blood to the brain is disrupted. Hence we see that unconsciousness is due to the insufficient supply of blood to the brain.
The state of unconsciousness can be prevented by some measures. If somebody feels that he is about to faint, he should immediately lie down. If that is not possible, he should bend downwards and enclose his head in between the knees. Both these measures enhance the blood supply to the brain and as soon as the brain starts receiving proper quantity of blood, the chances of one's becoming unconscious reduce.
If somebody has become unconscious, he should be laid down and his clothes should be loosened. His head should be kept a little lower, while the legs should be raised a little high. This will increase the blood supply to his brain and he will regain consciousness. Once he is conscious, he should be given tea or coffee. If somebody has fainted because of head injury or heat stroke, he should be taken to the hospital immediately.