A drowsiness detection device and method for a person (4), having a digital camera device (2) and a control unit (5). The digital camera device (2) includes a video processor (6). The digital camera device (2) is arranged to detect the eyes (3) of the person (4) in a series of images. The video processor (6) is arranged to detect eyelid movements in the images and convert images of the eyelid movements to an electric signal (s(t)) which is transferred to the control unit (5) The control unit (5) is arranged to fit a modeled signal (y(t)) against the electric signal (s(t)) and to determine whether the modeled signal (y(t)) constitutes an eyelid blink. The control unit (5) uses a number of modeled signals (y(t)) determined to constitute an eyelid blink to determine whether the level of alertness has fallen below a certain threshold.
