It was earlier believed that brain cells begin to die after they have been without oxygen for only four minutes. But now scientists and doctors have observed that the brain does not die so fast. It just idles for some time. For instance, drowning victims pulled out of water after 40 minutes have revived with hardly any damage to the brain. What saves such drowning victims is the mammalian diving reflex, which is observed in both human beings and sea animals. When the face is immersed in cold water, the cold stimulates a reflex action which slow down all activities within the body. The brain and the vital organs would then need less oxygen than usual. In addition, blood (with the oxygen it contains) is redistributed from the arms and legs to the brain and other vital parts.
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