Methods and systems for monitoring a driver of a vehicle using a driver state monitoring (DSM) system. The DSM system includes a sensing unit that senses biological information of a user of a vehicle. The DSM system also includes a controller that determines a drowsy state of the user based on the sensed biological information. The controller also determines a current condition of traffic and outputs information recommending rest for the user based on the determined drowsy state of the user and the determined current condition of traffic. The controller monitors the traffic and determines a rest state of the user, and outputs an alarm based on monitoring the traffic and the determined rest state of the user.
