As-Suyuti in "Medicine of the Prophet" said, " According to physicians the temperament of the soul should follow the constitution of the body, as has already been said. When the body is mid-way between hunger & satiety, sleepiness and wakefulness, and a balance is present, then the soul is brisk and agile and eager for what is good. But when it is loaded with excesses and extravagances, then the soul is distraught. And therefore, the Prophet [pbuh] said: I sleep and I get up: I fast and I break my fast. This is a traditional saying.”