Blue and yellow light, particularly from sunlight, are beneficial for setting circadian clock mechanisms early in the day.

“morning sunlight has and that evening sunlight has and without doing a whole tutorial when the sun is low in the sky So-Cal low solar angle sunlight you'll notice if you take a picture with your phone provid it's not a cloudy day you'll see that there's a lot of blue yellow contrast and that's the optimal stimulus that said if it's overcast out you should still get outside because some of those W lengths are coming through even though you can't perceive the blue and the yellow”

“You can, in theory, get it all from artificial lights, but there are some special qualities about sunlight that make sunlight the better stimulus.”