A user device may be used to prevent a driver of a vehicle from driving while drowsy. The user device may create a driver profile for the driver and collect driving data while the driver is driving the vehicle. The driver profile may include information regarding the driver's propensity to drive while drowsy and the driving data may include information regarding whether the driver is exhibiting drowsy behaviors and how long the driver has been driving continuously. The user device may determine whether the driver is drowsy based on the driver profile and the driving data, and may respond in one or more ways, such as by altering the driver with an audio signal, providing the driver with a map to a nearby rest area, activating a braking system of the vehicle, warning nearby drivers about the driver being drowsy, contacting a parent or guardian of the driver, etc.