what is happening in your brain when you lose consciousness?

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Was curious about what causes you to gradually lose hearing and sight for a few seconds

Edit: more accurate word would be fainting I think, not native

In: Biology
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Need to know more context. Like from getting a head injury?

To cover some basic situations, cutting off blood flow quickly stresses the cells in your brain. Can’t really sustain consciousness if the basic task of being alive is not going so well. It takes a lot of energy to sustain brain activity.

From getting hit in the head it’s because your brain was injured. You try doing work when someone kicks you in the gut haha. The networks get interrupted bc of injury. If it’s real bad, you may have permanent brain damage. Mild is concussion. But don’t be tricked, concussions are bad too. They can really fuck you up. Which makes sense: injuring your brain is bad.

Sleep: it’s part of a normal cycle of activity. Your brain is just going into a different operating mode basically. Normally it’s in “produce consciousness mode.” Sleep is “let’s clean stuff” mode. It has specific patterns of activity it goes through during that time.

Last bit of info: consciousness is still mysterious. But we do know for sure that you need a functioning reticular activation system in the brain. If you damage that, no consciousness ever again. It’s in the brain stem.

In order to be conscious you need nearly half of the brain cells in your cerebral cortex to be active at any given time. If you fall below this level of activity, you lose consciousness. Other parts of the brain that control vision and hearing require a certain threshold in order to function too.

If you’re talking about losing hearing and sight for a few seconds when standing up (a so-called “head rush”), this is caused by reduced blood flow to the brain. When you stand up gravity pulls blood down to your legs and arms. The lack of blood flow in the brain means cells aren’t getting oxygen and nutrients, so they can’t function. Your body quickly fixes this by tightening blood vessels in your legs to squeezes the blood back up to your head. Imagine if you squeezed the bottom of a half-full water bottle. Once blood flow to your brain is restored everything starts working again.

Usually brain goes “emergency mode” and shut down non-essential functions. Essentials are mostly the brain itself, and making internal organ work. So if for any reason your brain comes to the conclusion it can’t keep you working, it just focus on not letting you die. Minimize losses and hope that whatever is the cause of your current distress is not lethal.

The most common reason the brain goes in emergency mode is in case of lack of oxygen (choking, strangulation, water in the airways,…), your brain being shaken too hard, or general lack of any life required component. It can also be a response to sensory overload, if it gets overwhelmed. At that point, it basically act like a computer rebooting.