Teaching with Sleep Deprivation

I was wondering how schools and staff perceived substitute teachers who attempt to work with sleep deprivation, how likely they are to put a negative report on you if they find out?

Today, an RSP teacher walked in to the classroom while I was doing a read aloud and she notice my energy was low and slurring some sentences. This was in the afternoon after lunch, I was already exhausted by then working with the little ones.

Getting paid once a month + not get paid holidays + 10.25% pension contribution + University aka Masters program hasn't paid out my grant $$ = Working two jobs sacrifice plus school.

I need the money, but I'm definitely taking the day off tomorrow from subbing since I can't called out from other job tonight yet.