This is when someone (usually an early bird) discriminates against another person due to their sleeping pattern. They don't realise that not everyone can wake up at the ass-crack of dawn.
Person 1: You're so lazy, all you do is sleep all day.
Person 2: I work in the night stop partaking in sleepism.
Person 2: I work in the night stop partaking in sleepism.
by British fooker April 21, 2020
Get the sleepismmug.