misses a Salah (Prayer) due to sleeping or oblivion, it is Wajib (obligatory) on them to make it up whenever they remember it or wake up and they should not delay it until any other time. Proof for the foregoing is a Hadith in which the Prophet (peace be upon him) said:
Whoever misses a Salah due to oblivion or sleep, they have to offer it when they remember it. There is no Kaffarah (expiation) for it other than this.
May Allah grant us success. May peace and blessings be upon our Prophet Muhammad, his family, and Companions.