A system (1,21) for transmitting a notification to a user device, said system (1,21) being configured to determine a state of a light source, said light source being comprised in a smart lighting system (41,42), said system (1,21) comprising: at least one input interface (3,23); at least one output interface (4,24); and at least one processor (5,25) configured to: - receive user information via said at least one input interface (3,23), - determine that a user is away from home based on said user information, - receive light information from said lighting system (41,42) via said at least one input interface (3,23), said light information being indicative of said state of said light source, characterised in that said at least one processor is further configured to: - determine, based on said light information, that said light source is on while said user is away from home, - if it has been determined that said light source is on while said user is away from home, determine what caused said light source to be turned on, by determining based on an indication provided by the smart lighting system, a source of a control command to turn on the light source, - after said cause has been determined, decide whether or not to notify said user in dependence on said cause, and - after said decision has been made, transmit, via said at least one output interface (4,24), said notification to said user device of said user in dependence on said decision; wherein said at least one processor (5,25) is configured to determine what caused said light source to be turned on by: - determining whether user control or automatic control caused said light source to be turned on, or - determining a name associated with an action of turning on said light source, an event that caused light source to turn on, and/or a source of a control command to turn on said light source. at least one input interface (3,23); at least one output interface (4,24); and at least one processor (5,25) configured to: - receive user information via said at least one input interface (3,23), - determine that a user is away from home based on said user information, - receive light information from said lighting system (41,42) via said at least one input interface (3,23), said light information being indicative of said state of said light source, - receive user information via said at least one input interface (3,23), - determine that a user is away from home based on said user information, - receive light information from said lighting system (41,42) via said at least one input interface (3,23), said light information being indicative of said state of said light source, characterised in that said at least one processor is further configured to: - determine, based on said light information, that said light source is on while said user is away from home, - if it has been determined that said light source is on while said user is away from home, determine what caused said light source to be turned on, by determining based on an indication provided by the smart lighting system, a source of a control command to turn on the light source, - after said cause has been determined, decide whether or not to notify said user in dependence on said cause, and - after said decision has been made, transmit, via said at least one output interface (4,24), said notification to said user device of said user in dependence on said decision; - determine, based on said light information, that said light source is on while said user is away from home, - if it has been determined that said light source is on while said user is away from home, determine what caused said light source to be turned on, by determining based on an indication provided by the smart lighting system, a source of a control command to turn on the light source, - after said cause has been determined, decide whether or not to notify said user in dependence on said cause, and - after said decision has been made, transmit, via said at least one output interface (4,24), said notification to said user device of said user in dependence on said decision; wherein said at least one processor (5,25) is configured to determine what caused said light source to be turned on by: - determining whether user control or automatic control caused said light source to be turned on, or - determining a name associated with an action of turning on said light source, an event that caused light source to turn on, and/or a source of a control command to turn on said light source. - determining whether user control or automatic control caused said light source to be turned on, or - determining a name associated with an action of turning on said light source, an event that caused light source to turn on, and/or a source of a control command to turn on said light source.