It would be dark soon at the Coney Island Houses, the fourth night without power, elevators and water. Another night of trips up and down pitch-black staircases, lighted by shaky flashlights and candles. Another night of retreating from the dark.

On the second floor of Building 4, an administrative assistant named Santiago, 43, who was sharing her apartment with five relatives, ran through a mental checklist. Turn the oven on for heat. Finish errands, like fetching water for the toilet, before the light fades.

“We don’t dare throw out garbage at night,” she said. “We make sure everything’s done.”

Elsewhere in the building, Sandra Leon, 35, a mother of two, kept an eye on her door fearing another attempted break-in. Victor Alvarez, 60, waited for any word of his wife, Lucet, who suffers from schizophrenia and had disappeared into the wreckage-strewed neighborhood. And Marilyn Smalls, 48, sipped a room-temperature Corona that she had liberated from a gas-station trash bin the day before, along with sodas and bags of beef jerky — which drew neighbors knocking, as word of the haul got out.

Perhaps more so than in any other place in the city, the loss of power for people living in public housing projects forced a return to a primal existence. Opened fire hydrants became community wells. Sleep-and-wake cycles were timed to sunsets and sunrises. People huddled for warmth around lighted gas stoves as if they were roaring fires. Darkness became menacing, a thing to be feared.