What is the solution to the problem of being unable to wake up for Qiyam al-Layl (night prayer) and Fajr, despite reciting adhkar (remembrances) and striving earnestly to rid oneself of sins?

The way to erase sins is sincere repentance that fulfills its conditions, for the Prophet, peace and blessings be upon him, said: "The one who repents from sin is like one who has no sin." So, you must abandon sins, regret them, resolve not to return to them, and restore the rights of people. Seek Allah's help, adhere to His remembrance, accompany good people, and strive against yourself in obedience to Allah, for He, the Most High, said: "And those who strive for Us - We will surely guide them to Our ways." Whoever intends to perform the night prayer and is overcome by sleep will have the reward written for him. If you take the means to wake up and miss the prayer, there is no sin upon you, and you must perform it when you wake up.