M. Johns, A. Tucker, R. Chapman. A New Method for Monitoring the Drowsiness of Drivers. 2005 International Conference on Fatigue Management in Transportation Operations. Seattle, September 2005.
Abstract
Drowsiness is the intermediate, fluctuating state between alert wakefulness and sleep. It is implicated in many road accidents, but there is no generally accepted method for monitoring drowsiness objectively while driving. Objective: to describe a new method for monitoring the drowsiness of drivers continuously (Optalert™) using a new scale of drowsiness (The Johns Drowsiness Index or JDI). Methods: eye and eyelid movements were monitored by an infrared reflectance method using transducers housed in a light frame, such as would be worn with prescription lenses or sunglasses. The JDI (range 0-10) is based on a combination of variables characterizing eyelid movements during blinks, particularly the ratios of amplitude to maximum velocity (AVR) of eyelid closure and reopening. These are newly described patented variables that do not require individual calibration. Optalert™ recordings were made while 8 volunteers drove in a simulator for 45 min when alert and after sleep deprivation for up to 30 hr. Other recordings were made in commercial truck drivers, driving their usual routes and schedules at work. Results: In alert drivers, driving without incident, the JDI varied between about 0.5 and 4.0. Driving was impaired after sleep deprivation, and there were 61 drive-off-the-road “crashes” in the simulator, all of which could have been preempted with a warning when the JDI reached 4.5, particularly >5.0. A truck driver was also recorded on the road with a JDI >5 when he reportedly fell asleep at the wheel without crashing. Conclusion: trials in a driving simulator and with trucks on the road have shown that Optalert™ can monitor the drowsiness of drivers continuously and could potentially prevent crashes by prompting drivers to implement a drowsiness management strategy before they fall asleep at the wheel and crash.
