M.W. Johns, A.J. Tucker, R.J. Chapman, N.J. Michael, C.A. Beale. A New Scale of Drowsiness Based on Multiple Characteristics of Blinks: The Johns Drowsiness Scale. Sleep, 2006; 29 (Suppl): A365.
Introduction
Drowsiness is the intermediate state between alert wakefulness and sleep, to be distinguished from fatigue. Although drowsiness is believed to be the cause of many highway crashes, there is no generally accepted method for measuring it in people while they are active.
Johns (1,2) has previously reported on the use of amplitude-velocity ratios for measuring the relative velocity of eye and eyelid movements during blinks, and of eye movements during saccades. These ratios change with drowsiness in ways that do not require calibration for individual subjects
We describe here a new scale, the Johns Drowsiness Scale (JDS), that measures different levels of drowsiness continuously, particularly in people who should remain alert, e.g. while driving. It is based on a combination of oculometric variables, including the relative velocities of eye and eyelid movements, measured by a new method of infrared reflectance oculography (Optalert™) (1,3).
