A light generating system comprising (i) a light generating device configured to generate device light having a controllable radiant flux and a controllable spectral power distribution, and (ii) a control system configured to control the radiant flux and the spectral power distribution of the device light ; wherein: - a ratio B/Y of the device light is defined as a ratio of a radiant flux of the device light in the 450-500 nm wavelength range and of a radiant flux of the device light in the 550-600 nm wavelength range; - in a first operational mode of the light generating system the control system is configured to change from a first device light setting to a second device light setting, different from the first device light setting; - the first device light setting and the second device light setting are selected from: (a) a high radiant flux first setting (S 1 ) wherein the device light is first light with a first radiant flux I 1 and a first B/Y ratio R 1 ; and (b) a low radiant flux second setting (S 2 ) wherein the device light is second light with a second radiant flux I 2 and a second B/Y ratio R 2 ; - I 2 < I 1 , and R 1 < R 2 ; characterized in that : - in a second operational mode of light generating system the control system is further configured to change from a third device light setting to a fourth device light setting, different from the third device light setting; - the third device light setting and the fourth device light setting are selected from: (a) a high radiant flux third setting (S 3 ) wherein the device light is third light with a third radiant flux I 3 and a third B/Y ratio R 3 ; and (b) a low radiant flux fourth setting (S 4 ) wherein the device light is fourth light with a fourth radiant flux I 3 and a fourth B/Y ratio R 3 ; and - I 4 < I 3 , and R 3 > R 4 . - a ratio B/Y of the device light is defined as a ratio of a radiant flux of the device light in the 450-500 nm wavelength range and of a radiant flux of the device light in the 550-600 nm wavelength range; - in a first operational mode of the light generating system the control system is configured to change from a first device light setting to a second device light setting, different from the first device light setting; - the first device light setting and the second device light setting are selected from: (a) a high radiant flux first setting (S 1 ) wherein the device light is first light with a first radiant flux I 1 and a first B/Y ratio R 1 ; and (b) a low radiant flux second setting (S 2 ) wherein the device light is second light with a second radiant flux I 2 and a second B/Y ratio R 2 ; - I 2 < I 1 , and R 1 < R 2 ; characterized in that : - in a second operational mode of light generating system the control system is further configured to change from a third device light setting to a fourth device light setting, different from the third device light setting; - the third device light setting and the fourth device light setting are selected from: (a) a high radiant flux third setting (S 3 ) wherein the device light is third light with a third radiant flux I 3 and a third B/Y ratio R 3 ; and (b) a low radiant flux fourth setting (S 4 ) wherein the device light is fourth light with a fourth radiant flux I 3 and a fourth B/Y ratio R 3 ; and - I 4 < I 3 , and R 3 > R 4 . - in a second operational mode of light generating system the control system is further configured to change from a third device light setting to a fourth device light setting, different from the third device light setting; - the third device light setting and the fourth device light setting are selected from: (a) a high radiant flux third setting (S 3 ) wherein the device light is third light with a third radiant flux I 3 and a third B/Y ratio R 3 ; and (b) a low radiant flux fourth setting (S 4 ) wherein the device light is fourth light with a fourth radiant flux I 3 and a fourth B/Y ratio R 3 ; and - I 4 < I 3 , and R 3 > R 4 . <EOS>