[malux85]

That's interesting! I have a similar but not nearly as severe symptom caused by lack of sleep - the first thing to go for me is spelling.

Weirdly I can still code easily, even keeping in my head high level module interactions and abstractions, to low level implementation details, but I'll occasionally stop, stare at a word, convinced that it's spelt wrong, google it and see its correct, and go back and stare at it - because it just feels wrong.

When I've reached this point, I know it's time to break!