How long would the brain survive if its cooling system shut down?

The brain is highly sensitive to temperature and requires a consistent cooling system to function properly. If the cooling system, which primarily relies on blood flow to regulate temperature, were to shut down, the brain would begin to suffer from a lack of oxygen and nutrients very quickly. Typically, studies indicate that the brain can survive without adequate cooling or blood flow for about 20 minutes before irreversible damage occurs.

The choice indicating approximately 40 minutes suggests a more extended period than is widely accepted by neuroscientific research, which generally notes that critical functions begin to deteriorate rapidly after just a few minutes without oxygen. While some cells within the brain might survive longer in a reduced oxygen environment, significant function loss and permanent damage usually occur much sooner. Therefore, recognizing the sensitivity and acute vulnerability of the brain to interruptions in its cooling and oxygen supply helps clarify the reasoning behind this time frame.