1. A monitoring system for monitoring and/or predicting drowsiness of a driver of a vehicle or a machinery operator, comprising: a set of infrared or near infrared light sources, each light source arranged to direct light towards an eye of a driver or operator; the set of light sources adapted to emit light in separate time slots of a repetitive time frame; an image sensor arranged such that light reflected from the eye can be captured in an image; an image processing unit adapted to extract information of the light reflected from the eye; and a determining unit adapted to determine a drowsiness index based on the extracted information.