A method and a control unit are provided for detecting when the driver of a motor vehicle becomes inattentive. In order to be able to reliably draw conclusions about the presence of inattentiveness of the driver, it is proposed to observe not only a steering inactivity phase but also a steering action which follows the steering inactivity phase. A detected implementation of the steering inactivity phase and of the steering action are logically combined with one another, and the result of this logic combination is then used as a measure of the severity of the inattentiveness of the driver. In addition, the measure of the severity of the inattentiveness of the driver depends on at least one driver-specific parameter which is determined during the execution of the method. The inattentiveness of the driver can also be detected during the time interval in which the at least one driver-specific parameter is determined.