Many trials have been completed by Optalert Pty Ltd and others to validate the Johns Drowsiness Scale (JDS) as measured by the Optalert system of infrared (IR) reflectance oculography.
Relationship Between Blood Alcohol Concentration and JDS
Swinburne University of Technology, Drug and Alcohol Research Unit, performed a study in which 19 volunteers drank progressively more alcohol during a period of 6 hrs in the evening (6 pm to midnight). There was a linear relationship between JDS scores, measured during the JTV, and blood alcohol concentration measured by breathalyzer.
Relationship Between PERCLOS Measurements with the Copilot Video System and Optalert
Dr Mark Howard's group at the Institute of Breathing and Sleep, Austin Hospital, Melbourne, confirmed in laboratory experiments that the proportion of time that the pupils were at least 80% covered by the eyelids during eyelid closures that lasted at least 500 millsecs (measured by the Copilot video system) was highly correlated with the "percent time eyes closed" measured by Optalert.
Driving Simulator Studies at Monash University Accident Research Centre (MUARC)
An independent study by MUARC established that drowsiness induced by sleep deprivation affected the driving of 20 volunteers who drove for 45 min in the MUARC simulator when alert and when sleep deprived for 27-30 hrs. There was an exponential relationship between the proportion of time that the vehicle was outside the lane and the JDS score, measured from minute to minute as they drove.
The relationship between EEG Theta Waves and JDS Scores
A study was done in conjunction with the Sensory Neuroscience Laboratory, Swinburne University of Technology, Melbourne. Twenty volunteers performed JTVs when well rested and after being awake for 27-30 hrs. They had EEG recorded at the same time as Optalert recordings, while performing JTVs. There was a significant correlation between the theta power, measured by FFT, on 01 -02 derivatives of the EEG and JDS scores across all subjects-sessions. This was true whether the power was standardized for each subject or not.
Effects of Caffeine on JDS Scores
This study was performed in conjunction with Swinburne University of Technology. Fifteen volunteers with normal sleep habits and no reported sleep disorder were studied in a double-blind, cross-over study of the effect of a single dose of 200 mg of caffeine. Even though these normal subjects were not sleep deprived and had JDS scores in the normal range to begin with, there was a highly significant effect of the caffeine on JDS scores, suggesting decreased levels of drowsiness, beginning 30 mins after ingestion of caffeine and lasting 2 or 3 hrs.
