The Criterion for Sleep That Invalidates Ablution and Wiping Over Socks

Question:
May Allah reward you and bless you. Finally, he asks: What is the criterion for the sleep that invalidates wudu' (ablution) and from which a person must perform wudu'? And is it permissible to wipe over the known socks if they were put on while in a state of purity?

Answer:
The sleep that invalidates wudu' is deep sleep, whether one is lying down or sitting leaning on something such that if that thing were to fall, he would fall with it. This is what invalidates wudu' because at that point he does not trust himself, and it is a place where excretions are likely to come out. So sleep was made to invalidate wudu' because it is in the position of excretions coming out.
If it is deep sleep. As for light drowsiness of a person who is sitting and in control of himself, this does not harm, because the Companions (may Allah be pleased with them) used to wait for the prayer with the Messenger of Allah (peace and blessings be upon him) until their heads would nod, then they would stand up and pray without performing wudu', because they were sitting, and this is drowsiness, and few people fall into deep sleep from drowsiness. As for the rest regarding wiping over socks: if they are covering, if the socks cover the foot, covering the ankles, and everything below the ankles of the rest of the foot to the toes is level, and they were put on while in a state of purity, then the correct view is that he wipes over them, because the Prophet (peace and blessings be upon him) wiped over the leather slippers and over the socks.