LIGHTING CONTROL

According to a first aspect disclosed herein, there is provided a controller for controlling a first light source to emit light into a pupil of a human user in order to reduce at least one biological effect of light from a second light source on the human user, the controller comprising: a first input for receiving light property data indicating a property of the light from the second light source, said property being of a type which causes a biological effect on the human user; a second input for receiving pupil data indicating a size of the pupil of the human user; an output for sending control commands to the first light source; a processor configured to: determine, using the light property data received via the first input, that the light from the second light source has said property; in response to said determination that the light from the second light source has said property, determine, using said pupil data received via the second input, a current size of the pupil; and on condition that the current size of the pupil is determined to be larger than a minimum size, control the first light source to emit light not having said property into the pupil and thereby reduce the size of the pupil.