A method for determining a duration of a critical state of a driver of a vehicle. In this method, a state signal is read in, which represents a state of the driver detected using a sensor unit of the vehicle. It is subsequently checked whether the state signal represents the critical state or a non-critical state of the driver. If the state signal represents the critical state, a counter value of a counter representing the duration of the critical state is incremented. If the state signal represents the non-critical state, the counter value is held constant. If after the expiration of a reference hold time the state signal represents the non-critical state, the critical value is decremented.
