Statistically, driver drowsiness is classified as a major cause of vehicular accidents over world that affects, not only the driver, but also all people on the road. Mostly, the drowsiness results from non-readiness of drivers such as fatigue, distraction, and lack of sleep that may cause a loss of driver’s attention and even its sleepiness. Therefore, both researchers and market communities have put great efforts in order to early detect drowsy driver and avoid risk of accident. In this seminar, we provide an up-to-date review on emerging driver drowsiness monitoring systems proposed by both research and market communities. We classify and compare the proposed systems into two categories: sensing-based and visual-based. Finally, we discuss the advantages and disadvantages of each category while highlighting open issues which need further investigation in the future.