I recall reading about a bedside clock which offers a dim and subtle colour-shift at certain times; for example, it might glow red until 4am, amber from 4-6am,

I recall reading about a bedside clock which offers a dim and subtle colour-shift at certain times; for example, it might glow red until 4am, amber from 4-6am, and green from 6am onwards. The idea was to offer you you the ability to roughly determine the time to aid decision-making (as another commenter wrote, 'is it worth trying to go back to sleep?') without the alertness and/or anxiety that interacting with a gadget that tells the exact time.