Sleepiness is a subjective feeling, but it is worth trying to quantify at times. Society doesn’t want sleepy people working in critical jobs and the diagnosis of many dyssomnias is aided by knowing how sleepy people are.
The methods of quantifying sleepiness (aka drowsiness) generally rely on reports from the subject and observations of behavior rather than an fMRI or blood test or some other methods of looking inside the body.
The OSLER (Oxford SLEep Resistance test) is used by some researchers, as it is easier to administer than the MWT test. The detection of sleepiness is done by observing the patient’s behavior (response to a task of pressing a button after light flashes) rather than an EEG that the MWT test uses.
Pupillometry – measuring who wide the pupils are – is one method. Pupils expand and contract in response to light, and an alert, well rested person will have pupils that maintain their size during darkness. Sleepy people, on the other hand, will have pupillary oscillations in darkness. Preliminary work on this method for quantifying sleepiness has used a time period of 15 minutes for these tests and has been able to correlate the results to results from other sleepiness tests. However, pupillometry is not widely used, at least yet.