Sleep loss dulls alertness and coordination, and it can produce effects similar to severe intoxication, making actions like driving incredibly risky. But there's no clinical test for determining when someone is dangerously sleep deprived. Now, researchers report a step toward a non-invasive test for sleep deprivation in the Journal of Proteome Research. In a study of 20 men, they identified molecular differences in saliva after a full night's rest and 24 hours without sleep.