This large observational study demonstrated that hand hygiene compliance rates decrease over the course of a normal work shift. During the first hour of work, average compliance rates were approximately 43%. This dropped to 35% for the last hour of a 12-hour shift. In addition, more intense work shifts were associated with even bigger hand hygiene compliance drop-offs. The authors extrapolate these results to estimate that this compliance decrement could produce an additional 600,000 infections per year in the United States, resulting in up to 35,000 unnecessary deaths and $12.5 billion in excess costs. More time off between shifts led to better compliance rates during a subsequent shift. In this sample, 65% of the caregivers were nurses, and only 4% were physicians. Longer nursing shifts have previously been linked to other patient safety hazards. A prior AHRQ WebM&M commentary discussed challenges related to nursing staffing.