A week ago the curfew was also cut by two hours. The government said the curfew imposed on Cairo and 14 provinces would continue to end at 6:00 am.
Friday is a traditional day of protests, which usually begin after weekly Muslim prayers in the afternoon.
Authorities imposed the curfew on August 14, after violence erupted as security forces cleared supporters of ousted Islamist president Mohamed Morsi from two protest camps in Cairo.