How do I deal with the fear of making a mistake while exhausted?

You are operating on real people while running on almost nothing, and the fear that your tired hands could cost a life is heavy to carry. That fear is not weakness. It is proof you take the weight of this seriously, which is exactly the kind of person who should be holding the scalpel. You cannot fix the brutal hours by yourself tonight. What you can do is manage the parts within reach. Speak up when you are past safe limits. Lean on your checklists, your team, the systems built precisely because no one's hands are perfect when exhausted. You are not meant to be a lone hero running on empty. Take the rest you can, when you can, without guilt, because rest is part of doing the job well. And carry this fear as respect, not dread. The surgeon who fears the cost stays careful. The danger is the one who stops fearing it at all.