Egypt's capital prides itself on being a city that never sleeps, with crowds filling cafÃ©s and shops open into the small hours. So, the government is facing a backlash from businesses and the public as it vows to impose new nationwide rules closing stores and restaurants early.
Officials say the step is necessary to conserve electricity in a nation buckling under economic crisis and fuel shortages. But the decision has a strong undercurrent of social control: a desire by secular conservatives and Islamists alike to tame a population they see as too unruly, especially in a post-revolution atmosphere of strikes, protests and relentless demands on a beleaguered government.
Simply put, officials say, Egyptians should stop thinking they can do whatever they want, should go to sleep early and work in the morning.
"Egyptian life has turned nocturnal. Egypt should not be a nocturnal state, but a morning state like all countries," Legal Affairs Minister Mohammed Mahsoub, an Islamist, told reporters this week. "Energy, endeavour, labour and working hard should be the foundation."
"I call on all those thinking of opposing this to think about themselves - when should they wake up and go to sleep and when do their kids go to bed and wake up," he said. "This is really a behavioural issue."
He and other officials said the regulations will come into effect on Saturday. Under the new rules, shops would be required to close at 10 p.m. and restaurants and cafÃ©s at midnight. Businesses that have a tourism licence - which comes at a fee - would be exempted, meaning that most bars and upscale restaurants would stay open later. Violators would face a fine and, if they persist, closure.
But many are furious over what they see as an outright violation of the nation's psyche.
The proposed regulation has dominated the national conversation for weeks. Opponents, including chambers of commerce around the country, warn that it will damage an already suffering economy. Those who work night shifts will lose their jobs and, with Egyptians unable to shop late, sales will be stifled and small businesses will be forced to lay off workers, they say.
Others argue that it is biased against the poor, given that venues catering to rich Egyptians will be able to get tourist licences - which are not necessarily linked to actual business with tourists - at a time when small business owners are struggling to make ends meet because of the economic crisis.
"I wish that President Mohammed Morsi would make decisions that put the poor people ahead of the rich," said Ibrahim Mohammed, referring to the country's Islamist leader, now in his fourth month in office. Mohammed owns a street kiosk that sells cookies and cigarettes in central Cairo and stays open until midnight.
Opponents argue it will be virtually be impossible to enforce. Cairo, home to an estimated 18 million people, has hundreds of thousands of small businesses found on almost every street, alley and lane. Some, like eateries, juice shops and pharmacies, never close. Night-owl Egyptians are accustomed to being able to buy virtually anything, while away the time at a coffee shop or even get a haircut at any time of night.
Some warn that penalties could even spark violence at a time when Morsi's government is struggling to restore law and order amid the turmoil since last year's fall of longtime leader Hosni Mubarak.
"Maybe the government will try to force this on us, but that will never work with Egyptians," said Anwar Eid, whose spices and dry goods store in Cairo's middle class Dokki district has been in the family for seven generations.
In the working class neighbourhood of Imbaba, a waiter at a street cafe that's open 24 hours was fuming.
"What are the people who work the late night shifts supposed to do? Our salaries will go down. How will we find more work?" Ibrahim Saeed said. "We already have problems with unemployment and with crime. How will this help? The government issues decisions and that's it, they don't say why."
Officials have presented the regulation as a vital energy-saving step. Egypt has been plagued by widespread electricity cutoffs, in part because of overburdening on its facilities, just one of multiple breakdowns in the nation's infrastructure. Moreover, the government is trying to reduce crushing budget deficits as it struggles to revive an economy hard-hit since last year's revolution - and fuel for power plants is a heavy cost.
Local Development Minister Ahmed Zaki Abdin, a non-Islamist who served as a provincial governor under Mubarak, said closing up earlier would save the government more than $1 billion a year - though opponents have questioned whether the move would really conserve much energy.
But the move goes beyond economics to try to impose some control over a society in chaos.
"You can't have people staying up all night in cafes. People should be going to bed early so they can do their work," Abdin insisted.
"We can't just keep on doing whatever we want whenever we want. ... We're passing through tough circumstances. We have an economic crisis. We have an energy shortage. We have problems everywhere, strikes, unrest, demands. Can't anyone make a compromise?" he said in a TV interview this month.
Past governments have made attempts to regulate business hours in hopes of injecting a semblance of order to Cairo. But in the end, they backed down in the face of business opposition and public uproar. Some are convinced Morsi's government will do the same.
If implemented, the regulation could become an issue in parliamentary elections now expected early next year, as parties try to appeal to small businessmen and their employees angry over the early closing hours.
"This regulation is a huge mistake," said Ashraf Shaaban, who runs a falafel sandwich kiosk in Imbaba. "It is against the nature of the Egyptian people. We stay up late. We don't want a curfew."