You might think you can hide your late night video game sessions from your boss by pouring a pot of coffee down your throat, but those days may soon be over. There's now a blood test that can determine a person's level of sleep deprivation, which scientists hope can be used to learn just how much or little sleep a person has gotten. Researchers from the Sleep Research Centre at the University of Surrey were able to spot sleep-deprived participants with 92 percent accuracy, according to their findings published in the journal Sleep. The scientists say their test could help police identify tired drivers, but also assist employers in assessing the alertness of employees.