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Your spit can tell you how sleepy you are

Scientists at Washington Univeristy have identified the first biochemical marker linked to sleep loss, an enzyme in saliva known as amylase.
According to the researchers, amylase production increases in activity with prolonged sleep deprivation.
The research was conducted initially on fruit flies and later on humans. The same results were found.
Just like humans, fruit flies deprived of sleep will try to make up for the loss by sleeping more the next day. Paul Shaw and his team of researchers looked for markers of this sleep debt in saliva.
Why saliva? The brain areas that regulate sleep drive also send signals to the brain areas that regulate salivation.
Researchers subjected the flies to different kinds of sleep deprivation and looked for changes in activity in many different genes. Amylase levels consistently changed after sleep loss. They did further tests to make sure the level of amylase were influenced by sleep deprivation and not just wakefulness.
To determine the validity of the research in people, humans subjects were kept awake for 28 hours. They too had increased amylajects allowed to sleep normally.
“Despite the tremendous medical and public health consequences of sleep debt, its measurement in humans relies upon unreliable subjective rating scales and expensive, often impractical sleep laboratory testing. Simple, easily accessible biomarkers for sleep debt in humans would revolutionize our ability to conduct research on the causes and consequences of sleep deprivation and provide clinicians with valuable new tools for diagnosing and assessing treatment efficacy in patients with sleep disorders,” said study collaborator Dr. Stephen L. Duntley.
Study published in the December 26, 2006, vol. 103, no. 52 issue of Proceedings of the National Academy of Sciences (http://www.pnas.org/) PNAS | | 19913-19918
For a copy of the study go to: http://www.pnas.org/cgi/content/full/103/52/19913?maxtoshow=&HITS=10&hits=10&RESULTFORMAT=&fulltext=%22paul+J.+Shaw%22&searchid=1&FIRSTINDEX=0&resourcetype=HWCIT