In a 2011 study, researchers at Ben-Gurion University found that parole boards granted parole to about 70% of cases heard in the morning, but less than 10% of cases heard in the afternoon. This pattern held true regardless of the prisoners’ ethnic backgrounds, crimes, or initial sentences.

This pattern is due to a phenomenon called “decision fatigue.” As the day wears on, it became harder for the parole board to consider every aspect of a case thoroughly, so they defaulted to what seemed like the safest choice -- keeping prisoners in jail, or the status quo.