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How sleepiness is measured
Sleepiness still has no roadside test. But science is learning to measure it - in the clinic and in the body's biochemistry.
Alcohol has a breathalyser. Sleepiness does not.
What exists today to measure one, and what is missing for the other.
Clinical test for sleepiness: MSLT and MWT, EOC sleep centre. Biochemical marker: IRM Zurich, DOI 10.1021/acs.jproteome.5c01064
Two roads to measure it
MSLT and MWT
How quickly you fall asleep, and how long you can stay awake. Sleep centre tests, EOC.
IRM Zurich study
Looking in saliva for a biochemical signal of sleep deprivation. The path below.
The IRM study, in six steps
The problem
Sleepiness has no breathalyser. Unlike alcohol, it leaves no measurable trace at an accident scene.
The three conditions
Twenty volunteers, in random order, compared across three states: eight hours of sleep (control), six hours for four nights (restriction), one night awake (total deprivation).
The method
Saliva is analysed by mass spectrometry. A machine learning model looks for the patterns that separate the conditions.
The result
Acute deprivation leaves a recognisable metabolic fingerprint: about twelve molecular features, clearest in the morning. Four nights of six hours’ sleep produced only slight changes.
The limits
It is a proof of concept. The sample is small and homogeneous, twenty young men. It must be validated in real driving conditions.
The direction
A step toward an objective marker of sleep deprivation; the link with sleepiness at the wheel is still to be shown. What can be measured can be prevented.
