Does it stay lit up all night long? Does the light fade as the hours pass throughout the night?

Is it a chemical reaction with the bleach and sunlight?

How often do they have to refill the bottle I wonder.

It only works when the sun is up - it takes a small beam of light and refracts it throughout an otherwise dark interior. It's a sort of mini-skylight-lightbulb. Pretty amazing technology - relevant to those whose lives are lived in spaces so densely packed that daytime is dark inside. The website says they last about 5 years.

The water is far from clean there and the bleach prevents the sunlight from encouraging bacterial/fungal growth. The bleach lasts as long as the bottle does.
On sailing ships of yore it was a prism usually solid glass, sometimes slightly tinged green as old glass was in those days.
Today (and for years) modern houses use what's known as Solar Tubes. A mini-skylight that can be very bright. I had several in my house and one thing I learned the hard way: don't put the solar tube over a ceiling fan's bade space or you'll get a constant and very annoying blanking of the light as each fan blade passes under it.
P.S. It is only as good as the sunlight that hits it. no sun, no light. There is no chemical reaction just rays passing through the bottle. The bottle's neck shape helps to collect more sunlight that's why it's placed neck up in the ceiling.

OMG
This forum is just a wealth of information. I am so impressed!

Damn........I'll be drilling holes in my corrugated roof all day tomorrow!
Think I'm kidding - we are third world here now, baby!