What should a student in Belgium do regarding the times of Maghrib and Isha prayers during Ramadan, given that Isha prayer extends until midnight, and the student wakes up at 5 AM?

You must be careful to perform the prayer on time, and use aids to wake up. If you miss a prayer due to sleep, make it up immediately upon waking, and in its proper order, for the Prophet, peace and blessings be upon him, said: "Whoever forgets a prayer or sleeps through it, its expiation is to pray it when he remembers it." As for sleeping before Fajr or at the time of Iftar (definition), it does not affect the validity of the fast as long as you intended it from the night.