How can doctors work 24+ hour shifts and be expected to maintain enough focus and alertness to manage people's health?

I didn't know this was a thing. It's ridiculous. You need a crazy amount of concentration just to be a doctor at all, let alone completing 24 consecutive hours of that. Where is the sleep? Where is the rest? Food? They're human too. I understand contuity of care but is it really worth it when that care is so strained? It's not healthy!

And add onto that the repercussions if they make a mistake? Someone's life could be on the line. They're expected to handle that responsibility for over a full day with NO time to recover?