When I wrote the previous post before Y”K I had not yet seen the Shem m’Shmuel who addresses himself to the problem of ta’aroves tov/ra and writes that on Y”K one can experience perfect clarity of birur if one only immerses in the kedushas hayom and takes advantage of it. The simcha that is felt at the conclusion of the chag (Tosfos quotes from Midrash that there is a din of having a seudah to celebrate the conclusion of Y”K) is directly proportional to the degree that we open our heart to this experience of tahara. However, that feeling only lasts if we protect it and do not let it dissipate, and here the Shem m’Shmuel is mechadesh that not only can the physical construction of a sukkah serve to nurture that feeling within the protective symbolic walls of kedusha, but involvement in learning Mes. Sukkah and the laws of sukkah also serves the same function.
I mentioned receiving Kisvei Mahart”z Chiyus as a gift from someone before R”H and noticed a beautiful kashe he raises in a footnote. The Rosh writes that the reason a bracha is not recited over sleeping in the sukkah is because there is always the chance that one will not be able to fall asleep, rendering the bracha l’vatalah. By the same logic, asks the M.C., how can we say a bracha of hamapil – why is there no concern that one will recite the bracha and not be able to fall asleep? I’m not sure why he leaves this as a tzarich iyun – I will leave it to the comments for suggestions of chilukim that are possible.