What is the ruling on a fasting person sleeping, whether for an obligatory or supererogatory fast, and does it diminish the reward of the fast?

There is no harm for a fasting person in sleeping during the day, whether their fast is obligatory or supererogatory. However, it is disliked to excessive in it so as not to miss acts of worship. Some jurists, such as Ibn Juzayy and ‘Iyad, have explicitly stated the dislike of excessive sleeping during the day for a fasting person.