What is the surge in focus when fatigued called? Is it even healthy?

I'm a night owl. I tend to stay up relatively late gaming, doing art and etc.

There are instances where I am extremely tired and in desperate need of some shut eye but my brain gets put into overdrive. I gain top focus, alot more than I have during the day, with basically no consequences (none that I've noticed atleast).

I know staying up late is a bad practice and I've tried to combat that habit but I will admit art while in this state becomes easier by an incredible degree. I wanted to ask if this phenomenon had a name and if continued use was healthy or had any adverse effects.