Disclosed herein is a method of detecting a microsleep event in a subject. The method includes determining a number of eye openness factors by measuring a number of distances between an upper eyelid and a lower eyelid of at least one eye over a time period. Graphical representations of the eye openness factors are then generated. Changes in the eye openness factors over the time period are correlated with a reference eye closure pattern indicative of the microsleep event. Also disclosed is a microsleep event detection device.
