Is there any Shariah problem with my sleeping after Fajr prayer and after returning from college before Maghrib prayer, while staying up at night until Fajr?

A Muslim must observe prayers at their prescribed times, and with the mosque congregation whenever possible. There is no harm in staying up late for studying, as long as it does not lead to missing the Fajr prayer or harming oneself, for the Prophet, peace and blessings be upon him, said: "Be keen on what benefits you, seek help from Allah, and do not be helpless."