The New York Times reported on August 31 that the air traffic controller involved in the tragic Comair flight, which killed 49 people, was working on only two hours of sleep. This brings to mind an important, but little recognized sleep disorder known as shift work sleep disorder.

With the invention of electricity, modern society has become a 24/7 world. The problem is that our biology makes this difficult. We have a circadian pacemaker, running on a 24-hour schedule, which makes us more...