Abstract: A device for detecting momentary sleep is shown. The device includes a video recording device for video-based monitoring of a person and of an eye area of the person, the video recording device being configured to record a sequence of pictures of the person and of the eye area and to output same to a threshold determination device. The threshold determination device is configured to derive one or more thresholds individually adapted to the person from the sequence of pictures. Moreover, the device includes a threshold evaluator configured to decide, on the basis of the one or more individually adapted thresholds, whether or not the person has momentarily fallen asleep, the one or more individually adapted thresholds being utilized for establishing whether or not the thresholds have been passed within the actual time curve of the eye opening and, thus, whether or not the person has momentarily fallen asleep.