Sleepiness and Sleep Deprivation - long been associated with an increased risk of injury - this commonly accepted theory might not be true – says a recent study by a University of Missouri, Columbia.

In this research, more than 2,500 patients, Daniel Vinson, professor of community and family medicine, found that patients who reported feeling sleepy were, surprisingly, less likely to be injured. However, patients who reported better sleep quality in the previous seven days also were less likely to be injured.

But patients who reported getting more sleep in the 24 hours before an injury than they did in the previous 24 hours were found to have a higher risk of injury.

"It could be that people who feel sleepy change their behavior," Vinson said. "If I'm feeling really tired, maybe I'll stop driving, maybe I won't play sports. If we're changing what we're doing when we're feeling tired, that may be what lowers our risk of injury."

Vinson interviewed injured patients and compared them to a separate control group who were matched by age, sex, location of the injury and time of the injury. Patients were asked about their sleepiness at the time of injury (whether they were tired, sleepy or drowsy). Patients and participants also were asked about their usual quality and quantity of that sleep. Patients were then asked the number of hours they slept in the 24 and 48 hours prior to the injury.

This doesn't mean that people should go driving when they're feeling tired," Vinson said. "Rather, it suggests that further research needs to be done. It's important for the public's safety that we understand the connection between sleep and injuries."