Gene becomes more active with sleep loss

It's been said that an objective measurement of sleep loss could like finding the Holy Grail. It's been elusive. Here is an article that discusses research showing that a particular gene is expressed more during sleep deprivation. And this gene product could be tested in saliva samples of humans someday. It is not a measurement of sleepiness, but could indicate if a person is sleep deprived. More testing will be needed to see if the gene would be more active in people who get enough sleep, but have an untreated sleep disorder like sleep apnea.