Ten p.m. arrives in Cairo’s Sayyida Zeinab neighborhood with the same dogged tenacity as it does anywhere else, but down the fluorescent shopping streets and in the sidewalk cafes, few people used to glance at the clock. It might have been near bedtime in other countries, but Cairo was practically still waking up.

That was summer in the past, season of sweat, and the city adapted its schedule. Days were for cooling inside, or at least avoiding the sun’s blitzkrieg. Nighttime offered mercy. Though the concrete sidewalks still belched up the day’s accumulated heat, the neighborhood came alive only after isha, the last of the five daily Muslim prayers. The day went on long into early morning.

Not this summer. With an energy shortage prompting the government to mandate earlier closing times, 10 p.m. now brings a dimming to Sayyida Zeinab: metal shutters are down or rolling toward the ground, turning the loudly colored, exuberantly lit storefronts to gray.

Years into an economic crunch that has left the government scrambling for dollars and made life a misery for all but the richest, Egypt is short on natural gas and funds to buy more, necessitating daily countrywide blackouts until a few weeks ago.

So, starting in July, orders came from on high: To save electricity, stores must close by 10 p.m. and cafes, restaurants and malls by midnight, slightly later on weekends. Only groceries and pharmacies are exempt.