One could argue that if you were solving a complex problem that particular day, and it bothered you enough, you would still be thinking about it before going to bed. Wouldn't that keep your mind alert. As far as light intensity and color goes, many Asian countries have daylight florescent tube lights in their homes just like the ones in offices in US. But no one's complaining about drastic sleep deprivation in Asian countries with bright lights emitting all sorts of spectra