> Timing of light and absence of light is critical - early morning light exposure greatly benefits people with SAD. This reminds me of another conversation on

> Timing of light and absence of light is critical - early morning light exposure greatly benefits people with SAD. This reminds me of another conversation on HN about color sensitivity in human vision: https://en.wikipedia.org/wiki/Color_vision https://en.wikipedia.org/wiki/Color_vision I imagine that waking up long after sunrise could affect our sensitivity to certain light spectrums to the point that "night owls" and "morning people" are seeing completely different colors, but calling them the same name. In other words, two people who wake up early in the morning might both perceive a certain color of orange as "dark / muted", while people who wake up later in the day might perceive that same color of orange as "bright". On the opposite side of the spectrum, the color blue may appear more vibrant to people who wake up early, because their vision is bombarded with yellow (sunlight) in the morning.