I say, and with God's success: His wiping is invalid; because the duration of wiping starts from the beginning of sleep, which nullifies the ablution, so does the wiping. Refer to: Tanweer al-Absar, Al-Durr al-Mukhtar, and Rad al-Mukhtar 1: 185, and Al-Hadiyya al-Alaiyya p. 40, and God knows best.