Blackouts happen because the brain's 'save' button is disabled.

Have you ever woken up after a heavy night of drinking and realized you cannot remember how you got home? This is a blackout. It does not mean you passed out; it means your brain stopped recording. Deep inside your brain is a tiny, curved structure called the hippocampus. Its job is to take what is happening right now and write it into your long-term memory, like hitting 'save' on a computer document. Alcohol temporarily pulls the plug on this saving process. You can still walk, talk, and argue, but your brain is not writing any of it down.