The frequency distribution is established over a first time interval. The normal frequency range is found from the distribution, the median of the normal range is calculated and a threshold time is found by adding a predetermined value to the median. Thus a minimum threshold time for a blink is established so as to extract the slow blinks as a function of the distribution frequency. A calculation module (30) calculates the ratio of the appearance of slow blinks to the total number of blinks during a second time interval subsequent to the first time interval. The ratio is put on a display (3) and is used by a sleepiness level discriminator (50) to give an alarm when the ratio exceeds a threshold.
Estimator of sleepiness of vehicle driver from eyelid movement