We have lights installed for use during the day. This light temperature (5000 Kelvin) will keep you awake and fit. At the end of the day lights can be switched to a warming, more calming level (2700 Kelvin). When it's time to go to bed you can turn on the night light. This is 1000 Kelvin and is dark red. With this light on you are still capable of sleeping and yet you can find your way around.
All following the Philips Lighting research who is world leading in artificial lighting.