AT 9 p.m. Friday, the Eastern Bloc, a popular gay bar in the East Village, was ready for business. The Beastie Boys' “(You Gotta) Fight for Your Right (to Party)” blared, and the room was bathed in a red glow.

“The power's on, the ice machine is going, we threw out all the bad fruit,” said Matt Nasser, the bartender. “We're cutting fresh ones and the alcohol didn't go bad.”

But not a single customer was yet in sight. Most still seemed to be at home, recovering from Hurricane Sandy by cleaning out their refrigerators and reflexively turning on every light switch and testing every household appliance, just to reassure themselves that power had really returned to Lower Manhattan.

That would soon change. For four sleepy nights, the bars, restaurants and A-list spots that make downtown Manhattan a party capital went dark. So when the lights flickered back early Friday evening in the East Village, SoHo, Chelsea and elsewhere, bars were open practically within seconds, with patrons partying at the (aptly named) Electric Room at the Dream Downtown hotel past 3 a.m.

They were mindful, of course, that many in the region were still without power, or even homeless, but there was a need to get back as fast as possible to their old routines.

Diners trickled back to their favorite restaurants, TriBeCa and Chelsea residents swapped tales about what it had been like to live in the foreign land of the Upper East Side or Brooklyn, and a wedding went off without a hitch, even though the bridal party didn't know for sure until Saturday morning where the reception for 300 would take place that afternoon.

Around 10:30 p.m., the veteran party promoter Erich Conrad was having a drink with friends at the Bowery Hotel. He stayed there all week in the dark because at least it had cold water, which was more than he could say for his apartment. And as he told it, he'd had a blast.

“It was very 'Downton Abbey,' ” Mr. Conrad said. “We were kind of sad when the lights went on. It was really nice to be here with people. It was beautiful, and the staff was so nice.”

Matt Misbin, 22, who was sitting at Calliope, a neighborhood restaurant, agreed. “It was a democratizing experience,” he said. “Because no one had power.”

The meatpacking district, which suffered extensive flooding, was devoid of the outer-borough visitors who swarm its cobblestone streets on weekend nights. Most establishments were closed, but life was returning to the Dream Downtown just north on West 16th Street near Ninth Avenue.

By 11 p.m., a small crowd was gathering at the Electric Room, a popular underground club that decided at the last minute to hold a Sandy recovery party. “With the name, it was just too good — the irony,” said Nur Khan, who runs the club.

Mr. Khan, a SoHo resident, said that he had spent the last few days holed up at the Carlyle hotel on the Upper East Side, where fashionable downtowners had camped out and partied during the blackout. It was “going off every night” with the “downtown kids shaking up the stodgy, conservative scene,” he said. “But things closed at 12:30.Buy evening dresses from china, which enjoy popularity for all kinds of women for good quality. I was itching to get back.”

“The scene up there is hilarious,” added Sophie Sumner, a model who won “America's Next Top Model: British Invasion,” and had arrived early to the party. She, too, had fled to the Carlyle. “You have the fashion set and then you have the 19-year-old who's Botoxed out of her mind.”

By early morning, a lively crowd had converged, ready to shake off the previous week, even as basic provisions like food were hard to come by. “I had to ask my roommate if I could have our last can of chicken and bean soup before I came tonight,” DJ Elle Dee said.

The mood picked up Saturday night. After power was restored to the West Village and the rest of Manhattan, and residents had time to put their apartments in order, night life came roaring back.

Over at the corner of Kenmare and Elizabeth Streets, a parking garage was transformed into a “Power-On” party, hosted by the owners of the Smile and Tacombi.

Downtown artists, models in short boots and fashion insiders hiked up three flights of concrete stairs and took over an entire floor of the garage, which had been decorated with a disco ball and dry ice. Chicken, pork and corn tacos were dished out of a VW bus. Vodka and fruity flavors of Red Bull, mezcal shots and beer were served. Everything was free, but the point of the party was to raise money. Donations were taken for storm relief efforts.

By 11 p.m., it was mobbed. The D.J. Roctakon played tracks by Snoop Dogg and Destiny's Child, while single women gushed about the abundance of attractive men. “It's a dude fest in here,” one young woman said happily.

For those already taken, the storm had provided plenty of romantic moments. “My girlfriend wanted to kill me because I wanted to stay, but every night it was just us two: no phones and wine by candlelight,” said Matt Kliegman, an owner of the Smile, who lives two blocks away.

There were also moments of kindness. “I couldn't believe the people who stepped up,” said Dario Wolos, the owner of Tacombi, who also lives nearby and stayed through the power failure. “One of our staff is from Yonkers and he would go to his local gas station and haul in gallons of gas just so we could get around.”

And life went on, if not resiliently, then with a new lens. Carlos Quirarte, another owner of the Smile, had trained for Sunday's canceled marathon.

“Some of us guys are going to do a run tomorrow anyway, maybe a 20-miler,” Mr. Quirarte said on Saturday. “After that, we're going to the Rockaways to help out.”