A control unit for use in a lighting system comprising a plurality of light sources (4a, 4b, 4c), the control unit comprising: an interface for communication with a notification service; and a control module, the control module configured to: control the plurality of light sources (4a, 4b, 4c) to emit light in accordance with background light settings; receive, via said interface, user selected notification light settings that are to be supplied to one or more of the plurality of light sources assigned as notification light sources by the notification light settings to provide a visual notification of an event transmitted from the notification service; compare the background light settings with the notification light settings in order to determine, based on a predetermined threshold, whether sufficient contrast will be provided; and determine based on said comparison that one or more of the background light settings and the notification light settings are to be modified such that the contrast between the background light settings and the notification light settings is enhanced; wherein the control module is configured to, in response to determining that the received notification light settings are to be modified, modify the received notification light settings to generate modified notification light settings, and control the one or more notification light sources in accordance with the modified notification light settings, and wherein the control module is configured to, in response to determining that the background light settings are to be modified, modify the background light settings to generate modified background light settings, and control light sources of the plurality of light sources other than the notification light sources in accordance with the modified background light settings. an interface for communication with a notification service; and a control module, the control module configured to: control the plurality of light sources (4a, 4b, 4c) to emit light in accordance with background light settings; receive, via said interface, user selected notification light settings that are to be supplied to one or more of the plurality of light sources assigned as notification light sources by the notification light settings to provide a visual notification of an event transmitted from the notification service; compare the background light settings with the notification light settings in order to determine, based on a predetermined threshold, whether sufficient contrast will be provided; and determine based on said comparison that one or more of the background light settings and the notification light settings are to be modified such that the contrast between the background light settings and the notification light settings is enhanced; wherein the control module is configured to, in response to determining that the received notification light settings are to be modified, modify the received notification light settings to generate modified notification light settings, and control the one or more notification light sources in accordance with the modified notification light settings, and wherein the control module is configured to, in response to determining that the background light settings are to be modified, modify the background light settings to generate modified background light settings, and control light sources of the plurality of light sources other than the notification light sources in accordance with the modified background light settings. control the plurality of light sources (4a, 4b, 4c) to emit light in accordance with background light settings; receive, via said interface, user selected notification light settings that are to be supplied to one or more of the plurality of light sources assigned as notification light sources by the notification light settings to provide a visual notification of an event transmitted from the notification service; compare the background light settings with the notification light settings in order to determine, based on a predetermined threshold, whether sufficient contrast will be provided; and determine based on said comparison that one or more of the background light settings and the notification light settings are to be modified such that the contrast between the background light settings and the notification light settings is enhanced; wherein the control module is configured to, in response to determining that the received notification light settings are to be modified, modify the received notification light settings to generate modified notification light settings, and control the one or more notification light sources in accordance with the modified notification light settings, and wherein the control module is configured to, in response to determining that the background light settings are to be modified, modify the background light settings to generate modified background light settings, and control light sources of the plurality of light sources other than the notification light sources in accordance with the modified background light settings.