The Prophet said, "No woman can fast (supererogatorily) without permission of her husband." After that he accounted for Fajr prayer after sunrise, saying. "We come of a family notorious for late rising (only after sunrise)". To this the Prophet said, O Safwan! Pray when you wake up from sleep". -Abu Da'ood
What is prohibited is to deliberately delay the prayer without a valid excuse until the end of its due time and the beginning of the time of the following prayer, such as delaying the Thuhr prayer until the ‘Asr prayer is due. The Prophet, sallallaahu ‘alayhi wa sallam, said: “ Negligence is when one does not offer the prayer until theIf the latter is the reason, then you ought to go to bed early to allow you to wake up for Fajr. You implied that if you were to wake up late, you don’t experience such fits. So, that is an indication you would have no such difficulties if you were to condition yourself to go to bed early. Thus, you will be able to wake up for Fajr. So we say: if you got up about five minutes or ten minutes before sunrise, and if you do tayammum you will manage to pray in time but if you do ghusl the time will end, we say that you should do ghusl even if the time will end, because the time for prayer in your case starts when you wake up, not from when the dawn breaks, because you are excused. tUZxSE.