Yosef Karo

“ We eat, drink, and sleep in the Sukkah all seven days, both day and night, and we do not sleep outside of the sukkah, even for naps. But one may eat an insubstantial meal outside of the sukkah. How much is an insubstantial meal? Approximately an egg's worth of a loaf of bread. And it is permitted to drink water and wine and eat fruit (even if it is made into a meal (own opinion) ) outside of the Sukkah. Those who are stringent and will not drink even water outside of the sukkah are praiseworthy. ”

“ In a place where he cannot sleep with his wife, as he does not have a dedicated sukkah, he is exempt. It is good to be stringent and to be there with his wife, just as he resides all year, if he can have a dedicated sukkah. ”

“ A dish made of the five species [of grain] , if they are made into a meal, they are considered a proper meal and require a sukkah. Rem"a: Concerning the practice nowadays to be lenient with respect to sleeping, where only the scrupulously observant sleep in the sukkah, there are those who say that it is because of the cold, for it is uncomfortable to sleep in cold places (Mordechai ch. "Hayashen") . It seems to me that this is because the mitzvah of sukkah applies to a man and his household, a man and his wife, similar to the way he lives the rest of the year. ”