What is the ruling of Islamic law on delaying Fajr prayer due to an illness that prevents one from waking up?

To wake up for Fajr prayer, sleep early and get enough rest, seek medical treatment for any ailments you have, recite the prescribed remembrances (adhkar) and some Quran before sleeping, firmly resolve to wake up for the prayer and ask Allah for assistance in this, and sleep in a state of purity (wudu'). If, after taking these measures, you are still unable to wake up, there is no sin upon you. You are required to make up the prayer immediately upon waking and it is not permissible to delay it.