Sukkah 26 - A guarantor needs another guarantor in turn

Someone who is sick is exempt from the obligation of a sukkah: he does not have to sleep there, and he does not have to eat there. Even his attendants can go out of the sukkah and sleep outside. One who feels discomfort - such as the smell of the floor - is not obligated to be in the sukkah. If so, why did we have to mention the sick person? Surely, the sick is uncomfortable. The difference is that the sick can take his attendants with him, but it does not apply to the attendants of an uncomfortable person. 

One can eat a light snack outside the sukkah but not take a catnap. But with tefillin, catnap is allowed; what is the difference? Is it because he can appoint an overseer who will wake him up? Rav Mesharshia objected: that's not an explanation - guarantor needs his own guarantor, and your overseer may fall asleep as well! Rather, one should not nap outside the sukkah because even a nap refreshes him and counts as sleep. With tefillin, the concern is that he should not pass gas, and that won't happen while catnapping.

Rabbi Yochanan ben Zakkai was extra strict with himself and ate and drank even small amounts only in the sukkah. Nevertheless, this kind of strictness is permitted and is not considered presumptuous.

Art: The Sick Child by J. Bond Francisco