Clinician fatigue is widely viewed as a risk to patient safety. This review summarizes research of fatigue in anesthesiologists. Anesthesiologists perceive longer shift length and overnight shifts negatively impact patient safety. Even in countries that have adopted legislation to limit shift length, anesthesiologists frequently reported working longer than allowed and not getting the full rest period between shifts. A culture that fosters awareness and prevention of fatigue can improve not only patient safety, but also physician well-being.