Sleep Loss Shows Up Somewhere Surprising

Spit Take: Red, bleary eyes and dark undereye circles are telltale signs we’re not getting enough sleep. Researchers at the University of Zurich have now found a way to measure fatigue in our mouth — more specifically, in our saliva. 

The Study: The research team gathered 20 healthy young males (ages 20 to 33) who regularly get seven to nine hours of sleep. They created three interventions, each separated by one week: one night of total sleep deprivation, four consecutive nights of sleep restricted to six hours, and control sleep of eight hours. Multiple saliva specimens were taken before and after each intervention for each participant and then analyzed using liquid chromatography. Researchers identified 10 molecular differences in saliva between sleep-deprived and well–rested participants.

The Takeaway: Researchers say these 10 differences create a “sleepiness fingerprint” that could be used to develop a rapid saliva test to gauge sleepiness before driving or operating machinery — like a version of alcohol breath tests. Drowsy driving kills more than 6,000 people each year in the U.S.

Keep In Mind: This was a small preliminary study that included only young men, but the next research phase will include a broader population.