Is it obligatory to rinse the mouth upon repeatedly waking up from sleep during fasting, if light-colored blood comes out of the mouth during sleep?

A fasting person must be careful not to swallow blood as much as possible. If some of it overwhelms her, her fast is not broken. She should rinse her mouth so as not to swallow saliva mixed with blood. The Shafi'is hold that whoever swallows saliva mixed with anything else, whether pure or impure, has broken their fast. If the blood is excessive and it is difficult to avoid, its effect is excused, and spitting it out is sufficient due to hardship.