Adrenaline

[Slowboathome]

CoolHands said:

His missus fell asleep

[The OG Jester]

Your 'old' brain is wired to skip past the 'new' brain if it perceives a threat so once your brain/body has identified 'the threat' you have a massive dump of adrenalin to fight, flight or freeze in some cases! This is how we end up with panic attacks as your logical brain hasn't had time to comprehend why your heart rate has gone from 50-70 bpm to 120/130 bpm.

You will probably also shake, sweat, and most likely need a st once you realise what's going on and start to calm down.

[Stealthracer]

Have you ever noticed that if you touch something hot and immediately pull your hand away, you don't feel the pain until afterwards?

That would imply that one part of the brain is working faster than another.