What happens if you read Ayatul Kursi before sleeping?

Reciting Ayatul Kursi Before Sleep

It is a Sunnah to recite Ayatul Kursi daily. Specifically, before going to bed, you should:

“When you settle down on your bed, recite Ayatul Kursi from the start to the end; Allah will designate a guardian angel for you who will remain with you until you awaken in the morning.” (Source: Bukhārī)