Does swallowing blood from the gums and teeth – especially during sleep – break one's fast, given the difficulty of avoiding it or the hardship of repeated rinsing, and is it necessary to make up the day if this occurs?

It is absolutely forbidden to intentionally swallow blood that has exited the mouth. It must be spit out and discarded because it is impure. If a fasting person intentionally swallows it, their fast is invalidated. However, if blood reaches the interior of the body unintentionally, whether during sleep or wakefulness, the fast is not invalidated by that, because it was not intentional. A fasting person must be careful not to swallow blood, but if it seeps in without their choice, it does not harm them.