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.