The streetlights outside your window make it safer to walk home at night, but they are not an unalloyed good.

Paul Bogard's 2013 book, The End of Night, argues that there are numerous deleterious effects of pervasive electric lighting. It disrupts the natural rhythms of the human and animal world, he argues, and allows the tyranny of toil to steal away our nights as well as our days. And, of course, it blots out the stars.

That last fact inspired Philadelphia actor Chris Davis' new one-man show, Bortle 8, which uses the quest for a sky free of light pollution as a means to illuminate his own inner gloom. The play follows his increasingly surreal efforts, with amateur astronomer John Bortle - who created the Bortle scale to measure star visibility - acting as Virgil to Davis' Dante.

The play was conceived during a bleak period after a breakup. Bortle 8 has been performed a few times in Davis' South Philly home, but he is constantly tinkering with it. The version he will perform this week is not final.

"What I like about the play is that it starts from a very conversational tone and it moves toward theatricality," Davis says. "The first half is talking about light pollution, and in the second you meet a scientist, and by the end there's a highly theatrical moment. It really runs the whole course. More than any of my other shows, it's the play I feel the most connection with the audience."

During the play, Davis riffs on the countless others who have looked up at the seemingly unblinking night sky - from Sir Francis Drake to Lucy, the early human forerunner - contrasted with the events both tectonic and mundane that consume his time and thought (from the complexities of health insurance to Vladimir Putin's military ambitions). Then he meets Bortle, they descend into the dark depths of the Delaware River, and things start to get seriously weird.