I think the worst time was when I worked on a work project through the night. It was at my previous employer, I was forced to work on legacy php projects I knew nothing about. Nobody could help me and I was always doing days over tickets which were just a pain in the ass in an old magic framework and a custom build cms :c.

I couldn't motivate myself for days and eventually when the deadline came I worked through the night and committed in the morning, then I jumped into bed. I realized that this was a big sign that I really had to quit, and switched companies several months later.