I forget where I saw this (think it may have actually been a video), but they said the latest versions could work with the lights off as it is still flickering the light, but just dinner than what we could perceive. Of course this could with the assumption that the source I hard it from was correct and if so, then it's probably only feasible with lab grade sensors to pick up signals that sensitive.

or UVs..!

...then wireless networking really will cause cancer.

maybe a deep violet right at the edge of the visible spectrum? all you would see is a faint glow

I'm not sure but I heard short wavelength (blue/violet) visible light has most impact on circadian rhythms.

If it's indeed the case, insomnia or any other kind of sleep disorder is not worth it.

Ok, but you'll be the one to explain to people who don't want to accept the ionizing/non-ionizing radiation distinction that this sort-of-UV is not the cancer-causing UV.