The OPTALERT Alertness Monitoring System is the culmination of more than 15 years of research into the physiology of drowsiness by OPTALERT founder and now Chief Scientist, Dr Murray Johns.
Dr Johns and the team of OPTALERT researchers developed the proprietary drowsiness detection algorithm based on new methods for measuring eye and eyelid movements. This led to the development of the “Johns Drowsiness Scale” (JDS); the world’s first validated scale of drowsiness in active people.
OPTALERT measures have been shown to be influenced by the following factors:
- sleep deprivation
- blood alcohol concentration
- circadian rhythmicity
- sedative drugs
- caffeine.
The scale of drowsiness as measured by the OPTALERT Alertness Monitoring System has been validated against a number of objective and subjective measures including:
- driving simulator performance
- psychomotor vigilance performance tests
- reaction time
- electroencephalography (EEG)
- electrooculographic (EOG) slow eye movements
- PERCLOS measurements derived from video camera images
- driver hazard perception
- self-reported sleepiness assessments.
Results of OPTALERT research and product validation has been widely published by both the OPTALERT research team and leading research institutions from around the world including:
- Division of Sleep Medicine, Brigham and Women’s Hospital and Harvard Medical School
- Monash University Accident Research Centre (MUARC)
- Institute for Breathing & Sleep (IBAS), Austin Hospital
- Centre for Accident Research & Road Safety – Queensland (CARRS-Q)
- School of Psychology, Psychiatry & Psychological Medicine, Monash University
- Drugs & Driving Research Unit & Sensory Neuroscience Laboratory, Swinburne University of Technology
- Royal Australian Air Force (RAAF): Institute of Aviation Medicine (AVMED)
- BHP Billiton / Caterpillar.
Contents
OPTALERT Research Team
- Monitoring Eye and Eyelid Movements by Infrared Reflectance Oculography to Measure Drowsiness in Drivers
- A New Method for Assessing the Risks of Drowsiness While Driving
- The Relationship between EEG Theta Waves and JDS Scores
- Use of an Ocular Measure for Monitoring the Drowsiness of Drivers
- The Circadian Rhythm of JDS Scores
- The Test-Retest Reliability of an Ocular Measure of Drowsiness
Division of Sleep Medicine, Brigham and Women’s Hospital and Harvard Medical School
Monash University Accident Research Centre (MUARC)
School of Psychology, Psychiatry & Psychological Medicine, Monash University, Victoria, Australia
- Night Shift Work and Drowsy Driving in Australian Nurses
- Subjective and Objective Assessments of Sleepiness Following Short-term, Partial Sleep Restriction
Institute for Breathing & Sleep (IBAS), Austin Hospital, Victoria Australia
- Sleep, Alcohol, Drugs and Driving
- Relationship between PERCLOS Measurements with the Copilot Video System and OPTALERT
- Dr Mark Howard’s Summary of Drowsiness/Alertness Monitoring Technologies
Swinburne University of Technology, Victoria, Australia
- Effects of Caffeine on JDS Scores
- Relationship between Blood Alcohol Concentration and JDS (2005 & 2007)
Centre for Accident Research & Road Safety – Queensland (CARRS-Q)
BHP Billiton/Caterpillar Fatigue and Alertness Technology Project
Royal Australian Air Force (RAAF): Institute of Aviation Medicine (AVMED)
OPTALERT Research Team
Monitoring Eye and Eyelid Movements by Infrared Reflectance Oculography to Measure Drowsiness in Drivers
Johns MW, Tucker A, Chapman R, Crowley K, Michael N (2007)
Published in Somnologie 11:234–242
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Drowsy driving is believed to be a major factor in road crashes, but currently cannot be assessed accurately. A new system of infrared (IR) reflectance oculography is described that uses transducers attached to a glasses frame to measure drivers’ drowsiness continuously on a new scale (JDS). Driving in a car simulator was investigated in relation to JDS scores per minute. Fifty volunteers had their eye and eyelid movements monitored while performing RT-tests when alert and drowsy. Multiple regression analysis of ocular variables, measured every minute in alert and drowsy conditions, was used to establish the drowsiness scale (JDS). Driving off the road in the driving simulator was the criterion for dangerous driving by 8 sleep-deprived drivers. The regression predicting conditions was highly significant (R = 0.70, p<0.0001). Mean JDS scores and mean RTs in all test conditions were highly correlated (r =0.70, n=88, p<0.001). There were 62 “off-road” events for 8 drowsy drivers, and 61 of them were preceded by JDS scores >5.
A New Method for Assessing the Risks of Drowsiness While Driving
Johns MW, Chapman R, Crowley K, Tucker A (2008)
Published in Somnologie 12: 66-74
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This study described how drowsiness was related to performance failures in two different kinds of reaction-time (RT) tests as well as during simulated driving tests. 31 healthy volunteers performed simple (SRT) and choice (CRT) RT tests for 15 minutes with and without sleep deprivation for 27-33 hours. Their drowsiness was measured as a JDS score (0-10) each minute. In a separate experiment, 15 healthy young adults simulated driving in a car for about 70 minutes when alert and when sleep-deprived while their drowsiness was also measured. After sleep deprivation, RTs increased and errors of omission (failure to respond within 2 seconds from the start of the stimulus) occurred more frequently in both the SRT and CRT tests, the frequency of driving off the road increased, and JDS scores also increased significantly. The risk per minute for each subject of making an error of omission in SRT tests and of driving “off road” in a car simulator increased progressively with JDS scores (p<0.001).
The Relationship between EEG Theta Waves and JDS Scores
Crowley KE, Johns MW, Chapman RJ, Tucker AJ, Patterson J (2008)
An Ocular Measure of Drowsiness and the EEG: Changes with Sleep Deprivation
Published in Sleep, 31 (Suppl): A119
A study was done in conjunction with the Sensory Neuroscience Laboratory, Swinburne University of Technology, demonstrating the relationship between EEG Theta Waves and JDS Scores. 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.
Presented at SLEEP 2008, 22nd Annual Meeting of the Associated Professional Sleep Societies, June 7-12, 2008, in Baltimore, Maryland, United States
[Download additional information presented at the conference]
Use of an Ocular Measure for Monitoring the Drowsiness of Drivers
Johns MW, Crowley KE, Chapman RJ, Tucker AJ, Hocking CA (2009)
Proceedings International Conference on Fatigue Management in Transport Operations: p130
[Link]
In the present study we investigated the JDS scores of 16 young adults driving in a car simulator with and without sleep deprivation. One-way ANOVA was used to compare JDS scores in alert drivers, those who were sleep-deprived but did not have any lane-departure episodes, and those who were sleep deprived and who had lane-departures. We also calculated the percentage of lane-departure episodes that were preceded by a JDS score of at least 5.0 during different periods, up to 5 or up to 30 min before such episodes. None of the 16 subjects had any lane departure episodes without having been sleep deprived, but six subjects had a total of 102 unintentional lane-departures after sleep deprivation. The mean JDS score for all subjects before sleep deprivation was 3.4 +/- 1.9 (SD). After sleep deprivation, the 10 drivers but who still did not have any lane-departures had a mean JDS score of 4.3 +/- 2.0, and the 6 drivers who had lane-departures had a mean JDS score of 6.5 +/- 2.2 (ANOVA, p<0.001; all post-hoc Scheffe tests, p<0.001). The percentage of lane-departure episodes associated with JDS scores of 5.0 or higher during the preceding 5 min was 88.2%, and that increased to 100% for 30 min before each episode.
This device provides an objective measure of drowsiness while driving, based on the driver’s JDS score each minute. In sleep-deprived drivers, the risk of unintentional lane departure, with all its potential dangers, is greatly increased when a JDS score of 5 or more has been reached during the preceding few minutes. This is consistent with our previous research which showed that the risk of performance failure increased exponentially with JDS scores. A cautionary warning at JDS = 4.5 could enable drivers to manage the earliest stages of their own drowsiness, of which they are often not aware, before they fall asleep at the wheel and crash. This device is being used by drivers in the road transport and mining industries in Australia and elsewhere.
The Circadian Rhythm of JDS Scores
Johns MW, Tucker AJ, Chapman RJ, Michael NJ, Beale CA (2006)
A New Scale of Drowsiness Based on Multiple Characteristics of Blinks: The Johns Drowsiness Scale
Published in Sleep, 29 (Suppl): A365
Performance of a vigilance task (JTV) every 3 hours over a period of 27 hours of wakefulness showed highly significant changes in JDS scores across time, particularly after the first 18 hours of wakefulness.
These changes in drowsiness scores were also in line with the occurrence of lapses in psychomotor performance.
Presented at SLEEP 2006, 20th Anniversary Meeting of the Associated Professional Sleep Societies, June 17-22, in Salt Lake City, Utah, United States
[Download additional information presented at the conference]
The Test-Retest Reliability of an Ocular Measure of Drowsiness
Johns MW, Crowley KE, Chapman RJ, Tucker AJ, Hocking CA (2008)
Published in Sleep, 31 (Suppl): A118
The aim of this investigation was to measure the test-retest reliability of mean JDS scores at different levels of drowsiness. 14 healthy volunteers (M/F=10/4, ages 21-32 yr) performed 15-min JTV test, twice within 2 hr under three different conditions, a “not sleep-deprived” condition on one day with tests at 1200 and 1400 hr after a normal night’s sleep, and two “sleep-deprived” conditions on another day after missing the previous night’s sleep with tests at 0945 and 1130 hr and again at 1440 and 1545 hr, i.e. after being awake for 27-33 hr. Repeated measures ANOVA for mean JDS scores showed a significant effect for Condition (sleep deprivation) (F (2,39)=5.049, p=0.01), but not for Session (test-retest) (F(1,39)=0.980, p=0.33), or Condition x Session interaction (F(2,39)=0.863, p=0.43). A paired t-test between test and retest mean JDS scores, combining all 3 conditions, showed no significant difference (mean diff = 0.19 +/- 0.19 standard error, n = 42, p>0.3), and there was a high intraclass correlation (r = 0.80, n = 42, p<0.001). The mean JDS score per 15-min JTV test increased after sleep deprivation and those scores were very reliable, at least in the short-term.
Presented at SLEEP 2008, 22nd Annual Meeting of the Associated Professional Sleep Societies, June 7-12, 2008, in Baltimore, Maryland, United States
[Download additional information presented at the conference]
Division of Sleep Medicine, Brigham and Women’s Hospital and Harvard Medical School
Real-time Drowsiness as Determined by Infra-reflectance Oculography is Commensurate with Gold Standard Laboratory Measures: A Validation Study
Anderson C, Chang A, Ronda JM, Czeisler CA (2010)
Published in Sleep, 33 (Suppl): A108
Professor Charles Czeisler’s group within the Division of Sleep Medicine, Brigham and Women’s Hospital and Harvard Medical School, examined the validity of JDS scores by assessing homeostatic and circadian change, in comparison to objective and subjective measures of sleepiness.
Fourteen healthy adults were phase-advanced (8h) using 90lux polychromatic light of different wavelengths before undergoing a 30h period of extended wakefulness under constant routine (CR) conditions. Participants wore the OPTALERT system throughout the CR, and completed bi-hourly neurobehavioral tests, including the Karolinska Sleepiness Scale (KSS) and Psychomotor Vigilance Task (PVT). JDS scores, Mean RT, lapses, and KSS scores were assessed for change over time. Average JDS scores in the 10-minute period preceding PVT/KSS tests were averaged to compare proprietary ‘low’ versus ‘cautionary’ scores in predicting subsequent performance and ratings of sleepiness. Average JDS scores revealed a significant main effect of time (P < 0.0005): the 27th-30th hours awake were significantly more drowsy compared to the 10th-18th hours awake (wake maintenance zone). A repeated measures ANOVA revealed a significant main effect of time, no main effect of test, and a significant test*time interaction (P < 0.0005). Tests following JDS scores p> 4.5 (cautionary level) were associated with increased mean RT (550.4ms vs. 2053.2ms), slowest 10% RT (1954.7ms vs 5330.4), lapses (4.2 vs. 10.2) and KSS (4.3 vs 6.5).
It was concluded that JDS scores fluctuated according to circadian and homeostatic sleep pressure. Average JDS scores above the cautionary level were associated with subsequent delayed responses time, lapses and subjective sleepiness when compared to those below the cautionary level.
Presented at SLEEP 2010, 24th Annual Meeting of the Associated Professional Sleep Societies, San Antonio, Texas, United States
Monash University Accident Research Centre (MUARC)
Driving Performance and the Johns Drowsiness Scale
Stephan K, Hosking S, Regan M, Verdoom A, Young K, Haworth N (2006)
Published in MUARC Report No. 252. The Relationship between Driving Performance and the Johns Drowsiness Scale as Measured by the OPTALERT System
An independent study by Monash University Accident Research Centre (MUARC) established that drowsiness induced by sleep deprivation affected the driving of 20 volunteers who drove for 70 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.
It was concluded that the OPTALERT system had high sensitivity for correctly classifying drivers as too drowsy to drive before the vehicle ran off the road. Furthermore, there were no off-road events for drivers who were classified as alert; indicative of high negative predictive value. High sensitivity and high negative predictive value are both very desirable attributes of a system that is designed to warn drivers of drowsiness.
School of Psychology, Psychiatry & Psychological Medicine, Monash University, Victoria, Australia
Night Shift Work and Drowsy Driving in Australian Nurses
Ftouni S, Sletton T, Howard, M, Lenne, M, Lockley S, Rajaratnam S (2010)
Published in Sleep and Biological Rhythms, 8: A57
Researchers from Monash University, Harvard Medical School, and the Austin Hospital investigated the extent of sleepiness and drowsy driving experienced during the commute to and from standard and non-standard (night shift) work hours in hospital-based nurses. OPTALERT was used to monitor drowsiness levels in fifteen volunteers during each driving commute to and from work.
Participants reported lower sleep quality and higher levels of sleepiness during episodes of night shift work compared to day shifts and days off. Self-rated sleepiness and JDS scores were higher during post-shift commutes compared to pre-shift commutes. Compared to commutes after day shifts, participants showed a higher incidence of JDS scores above cautionary (JDS greater than or equal to 4.5) and critical (JDS greater than or equal to 5.0) levels while driving home after night shifts. These findings demonstrate that night shift workers experience high levels of drowsiness while driving home after night-shifts, thus placing themselves and others at increased risk of motor vehicle crashes.
Presented at Sleep Down Under 2010 – Biodiversity of Sleep. Australian Sleep Association and Australian Sleep Technologists Association 22nd Annual Scientific Meeting, Christchurch, New Zealand, 21-23 October
Subjective and Objective Assessments of Sleepiness Following Short-term, Partial Sleep Restriction
Sletten TL, Segal AY, Redman JR, Lockley SW, Rajaratnam SMW (2009)
Proceedings International Conference on Fatigue Management in Transport Operations: p117
[Link]
Researchers from Monash University and the Division of Sleep Medicine, Brigham & Women’s Hospital and Harvard Medical School investigated the effects of short-term, partial sleep restriction on subjective and objective measures of daytime sleepiness. Preliminary results found that the adverse effects of partial sleep restriction were demonstrated by both self-awareness of sleepiness (Karolinska Sleepiness Scale) and objective measures of sleepiness (OPTALERT Drowsiness Scores and Electrooculogrophic slow eye movements). The researchers plan to extend the analysis to examine temporal changes in these measures.
Presented at “2009 International Conference on Fatigue Management in Transportation Operations: A Framework for Progress” Boston, Massachusetts, United States
Institute for Breathing & Sleep (IBAS), Austin Hospital, Victoria Australia
Sleep, Alcohol, Drugs and Driving
Howard, M, Stevens, B, Swann P, Wilkinson V, Barnes, M, Jackson, M (2010)
Published in Sleep and Biological Rhythms, 8: A4.
The aim of this investigation was to evaluate the relative effects of sleep restriction, acute effects from benzodiazepines and alcohol on driving performance and indicators of drowsiness. Eighteen current drivers undertook a 60 minute driving simulation (AusEd) and measurement of sleep latency (Osler) during the day under four conditions in a randomized cross over design, one week apart: baseline measurement; following sleep restriction to four hours; after benzodiazepine ingestion; and following alcohol (BAC of 0.05% and 0.08%). EEG and the percent of time with eyes closed (OPTALERT) were recorded during the tasks.
Sleep restriction to four hours for one night and acute benzodiazepine ingestion impair simulated driving performance to a similar degree to levels of alcohol that are illegal for driving. Physiological measures of drowsiness are affected by alcohol and benzodiazepines as well as sleep restriction, with previous studies suggesting that the combination of these conditions has at least an additive effect on driving impairment.
Presented at Sleep Down Under 2010 – Biodiversity of Sleep. Australian Sleep Association and Australian Sleep Technologists Association 22nd Annual Scientific Meeting, Christchurch, New Zealand, 21-23 October
Relationship between PERCLOS Measurements with the Copilot Video System and OPTALERT
Howard M, Clarke C, Gullo M, Johns M, Swann P, Pierce R, Kennedy G (2006)
Evaluation of Two Eyelid Closure Monitors for Drowsiness Detection
Published in Sleep and Biological Rhythms, 4 (Suppl 1): A13
Dr Mark Howard’s group at the Institute of Breathing & Sleep, Austin Hospital, 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 milliseconds (measured by the Copilot video system) was highly correlated with the “percent time eyes closed” measured by OPTALERT.
Presented at Sleep Across Time and Age. 19th Annual Meeting of the Australasian Sleep Association (ASA) & Australian Sleep Technologists Association (ASTA) 5-7 October, Perth, Australia, 2006
Dr Mark Howard’s Summary of Drowsiness/Alertness Monitoring Technologies
[Download]
Dr Mark Howard provides a formal statement on some of the published presentations from studies that have been undertaken by the Institute of Breathing and Sleep (IBAS) which have been part funded by VicRoads.
After surveying a range of “fatigue” accident risk reduction technologies VicRoads (www.vicroads.vic.gov.au) the Victorian Government State Road and Road Safety organisation decided to focus on Ocular dynamics as one of the most promising approaches to identifying an objective measure for fatigue accident risk. In 2006 VicRoads contracted IBAS to undertake assessments of eye closure technologies such as Video Monitoring, Co-Pilot and OPTLAERT.
Dr Howard writes, “[OPTALERT’s] Johns Drowsiness Score were related to crashes and attention lapses” and “recent studies have demonstrated that the [OPTALERT] Johns Drowsiness Scale can identify excessive drowsiness levels experienced by drivers who have experienced sleep restriction, alcohol ingestion, and benzodiazepine ingestion (Ref. Sleep and Biological Rhythms 2010; 8: A4).”
Swinburne University of Technology, Victoria, Australia
Effects of Caffeine on JDS Scores
Michael NJ, Johns MW, Owen C, Patterson J (2008)
The Effects of Caffeine on Alertness as Measured by Infrared Reflectance Oculography
Published in Psychopharmacology, 200: 255-260
This study was performed in conjunction with the Sensory Neuroscience Laboratory, Faculty of Life and Social Sciences, 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.
Relationship between Blood Alcohol Concentration and JDS (2005 & 2007)
Drugs & Driving Research Unit, Swinburne University of Technology, Victoria, Australia
Institute for Breathing & Sleep, Austin Hospital, Melbourne, Australia
Unpublished data
The Drugs & Driving Research Unit, Swinburne University of Technology, performed a study in 2005 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 breathalyser.
In 2007 the Institute of Breathing & Sleep (IBAS) at the Austin Hospital used OPTALERT to record objective drowsiness levels in 22 young drivers during the performance of two tasks, the Psychomotor Vigilance Task (PVT) and a simulated driving task, at different alcohol levels and following 24 hours sleep deprivation. The results showed that JDS scores (measured during performance of PVT) significantly increased after sleep deprivation, and at blood alcohol concentrations of 0.025%, 0.05% and 0.075%. The JDS during sleep deprivation was also significantly higher than that for the 0.025% and 0.05% BAC levels.
Simulated driving performance showed significant increases in JDS scores between the baseline condition (no alcohol) and all alcohol conditions. Increased JDS scores were also associated with increased variation in lane position, speed and crashes on the driving simulator. A similar relationship was also observed with reaction time, performance lapses and self-reported sleepiness (KSS).
This data suggest that JDS can be predictive of performance impairment due to alcohol intoxication.
Centre for Accident Research & Road Safety – Queensland (CARRS-Q)
Objective Sleepiness Predicts Performance on a Hazard Perception Simulator Task
Smith SS, Horswill M, Parker G (2009)
Proceedings International Conference on Fatigue Management in Transport Operations: p3
[Link]
The Centre for Accident Research and Road Safety Queensland (CARRS-Q) used OPALERT in their research to objectively measure the impact of sleepiness on a driver’s hazard perception skill. This is the first study to demonstrate a relationship between drowsiness and performance on a hazard perception test. This research showed that drowsiness directly impacts on the hazard perception of drivers, particularly in the early morning hours and is clearly a potential contributor to road crashes.
Presented at “2009 International Conference on Fatigue Management in Transportation Operations: A Framework for Progress” Boston, Massachusetts, United States
BHP Billiton/Caterpillar Fatigue and Alertness Technology Project
Cutting-Edge Technology to Warn of Approaching Drowsiness
Published in BHP Billiton Sustainability Report 2008: 65-66, 70-71
As part of a two year global study into fatigue technologies – BHP Billiton/Caterpillar Fatigue and Alertness Technology Project – the OPTALERT system was extensively tested in haulage trucks at the Mt Keith mine, part of Nickel West operations in Western Australia.
In November 2007, the study identified OPTALERT as the preferred technology solution for BHP Billiton to help detect operator drowsiness/fatigue.
Since the outcomes of this project were announced, a global supply agreement has been established with BHP Billiton. There are a number of sites in Australia and South America currently implementing the OPTALERT Alertness Monitoring System.
Royal Australian Air Force (RAAF): Institute of Aviation Medicine (AVMED)
A Drowsiness Detection System for Pilots
Corbett MA (2009)
Published in Aviation, Space, and Environmental Medicine, 80(2): 149
OPTALERT has worked with AVMED since January 2007 to develop a portable version of the OPTALERT Alertness Monitoring System for use in the aviation industry. A proof-of-concept trial was performed in a dynamic flight simulator configured to a PC9 aircraft and concluded that OPTALERT has the potential to be included in aircrew fatigue risk management systems.