The research on decision fatigue is straightforward enough to have entered popular understanding: the quality of human judgment declines over the course of a decision-making session, with later choices showing systematically worse outcomes than earlier ones regardless of the stakes involved. Judges issue harsher parole decisions late in the day. Shoppers make worse dietary choices at the end of a grocery run. Executives approve worse proposals in the final hour of a board meeting. The mechanism is neurological, not motivational — willpower and judgment draw on a shared cognitive resource that depletes with use.