Out-of-band switching of states of a computing device by a coupled peripheral device, are described. A sensor within the peripheral device may monitor an area in proximity to the peripheral device. A controller within the peripheral device may determine whether a user is present within the area. On determining the user to be present, a control signal may be generated. The control signal is conforms with the messaging protocol and causes the computing device to switch between an operational state and a low-power state. The controller may cause out-of-band transmission of the control signal to the computing device through the transmission interface.