The invention relates to a lighting system (1) comprising a lighting device (3) for emitting light in a high-power mode and for providing a further function like a sensing function in a low-power mode and a switch (4) connecting the lighting device with a power supply (2). The switch is switchable between a high-power state, in which a higher power is provided to the lighting device via the switch, which allows the lighting device to emit the light in the high-power mode, and which may be regarded as being an ON state, and a low-power state, in which a lower power is provided to the lighting device via the switch, which allows the lighting device to provide the further function, and which may be regarded as being an OFF state. Thus, for instance, a sensing function can be provided, even if the switch is in its OFF state.